Slardar
* Enigma can be a perfect counter-initiator with his ultimate. A perfectly timed Black Hole will turn the tide of any initiation, especially from heroes like; 
Spirit Breaker, 
Legion Commander, 
Axe, 
Puck, and 
Slardar.
Underlord
* Enigma's 
Midnight Pulse damage can make Underlord suffer heavy damage due to his high health.
* Enigma can catch Underlord and his team off guard with Midnight Pulse and 
Black Hole when they teleport using 
Fiend's Gate. And 
Atrophy Aura offers no defense against them.
* However, Enigma needs to approach Underlord carefully as Underlord can interrupt channeling of the Black Hole with 
Pit of Malice and can also use 
Firestorm to scout Enigma's location which can also put Enigma's 
Blink Dagger on cooldown if Enigma has no 
Black King Bar available to use.
Underlord
* 
X Marks the Spot will return Underlord or his teammate if they escape with Fiend's Gate.
Slardar
* 
Fortune's End applies a basic dispel which can be used to dispel Corrosive Haze, or even Slardar's own Guardian Sprint.
* 
False Promise is able to dispel Corrosive Haze and Slithereen Crush stun/slow from any allies Oracle chooses to cast it on.
* 
Fate's Edict can also be cast on Slardar to prevent him from proccing his Bash of the Deep.
Slardar
* Abaddon can cast 
Aphotic Shield on any of his allies to immediately dispel Corrosive Haze and/or the stun and the slow components of Slithereen Crush.
* All of Slardar's debuffs are also removed if Abaddon's 
Borrowed Time triggers.
Underlord
* Io can escape from Pit of Malice with Tether or Relocate.
* Relocate can counter Dark Rift's split pushing.
Slardar
* Slardar has high priority on building moblity items such as Blink Dagger rather than tank items. Zeus can easily deal large amount of damage to him if not caught out of position first.
Underlord
* 
Reaper's Scythe and 
Heartstopper Aura deal percentage-based damage, ignoring Underlord's high health.
* 
Ghost Shroud protects Necrophos from Underlord's damage from Atrophy Aura, and also amplifies all the healing Necrophos receives.
Underlord
* 
Winter's Curse and 
Splinter Blast can devastate Underlord's team when they're grouped up for Dark Rift.
Slardar
* 
Fire Spirits greatly reduces Slardar's already low starting attack speed (which Bash of the Deep relies on), making the laning phase very hard for him and discouraging Slardar from aggressively threatening lane kills.
* 
Supernova, ignoring Phoenix's lack of armor and Slardar's high damage single hits, is extremely hard for Slardar to take down on his own, especially after being hit by Fire Spirits.
* 
Icarus Dive is one of the longest distance escape spells in the game, and can help a good Phoenix escape from Slardar before he gets a Blink Dagger. However, the high cooldown means Phoenix is vulnerable to backstabs from any roamers after said spell is used.
* Slardar can interrupt an Icarus Dive from completing the flight with both of his stuns, however, likely leading to death if Supernova is on cooldown.
* A lot of the items a Phoenix builds throughout the game naturally counter Slardar. 
Shiva's Guard, 
Heaven's Halberd and 
Eul's Scepter of Divinity all stall Slardar's normal attacks in some way, while 
Spirit Vessel's percentage-based damage is good against his innate durability.
Underlord
* 
Glimpse will return Underlord or any of his teammates attempting to escape with Dark Rift if timed correctly.
* Underlord is a slow and low mobility hero, easy to set up 
Static Storm and 
Kinetic Field, preventing him from using his abilities as well as preventing him using Fiend's Gate to escape.
Underlord
* Firestorm will do little percentage damage to a small HP hero like Monkey King.
* All aspects of Jingu Mastery benefits ignore Atrophy Aura's base damage reduction.
* Monkey King can get on top of Underlord easily at any stage of the game.
Underlord
* 
Static Link greatly reduces Underlord damage, while benefits Razor himself, even when in Atrophy Aura's range.
* Underlord is a slow and low mobility hero, and cannot outrun Razor's high movement speed, easily for Razor to absorb his damage with Static Link to the maximum and burst him down from the bonus damages, combine with the armor reduction from 
Eye of the Storm .
Underlord
* As a frontline tank, the abilities of 
Underlord is surprisingly spell-cast heavy, and is often great for Rubick to steal.
* Firestorm is a great ability for farming, pushing and serves as a useful teamfight damage source, and even more so when its damage is amplified by 
Arcane Supremacy and 
Aghanim's Shard.
* It is worth mention that Firestorm has no visible effect on heroes other than damage, and the enemy team may easily mistaken the ability as casted by Underlord, resulting in unexpectedly soaking up more damage.
* Pit of Malice is a great area control ability in teamfights, capable of trapping multiple heroes in a hazard area.
* Underlord has no immediate reposition ability, and since he usually stays at the front, he can be an easy target for Rubick's Pit of Malice.
* Fiend's Gate, if stolen, grants Rubick's team great versatility around the map. Creating a surprise gank or appear as a group at the enemy backline during skirmish, escaping as a team from bad situations, or even taking Roshan or enemy highground unexpectedly, the possibility are endless with careful communication among Rubick's team.
Additional:
* All of Underlord's abilities are useful for Rubick to 
Spell Steal.
Underlord
* Tanky melee heroes that can easily be kited, which allows Outworld Destroyer to deal heavy damage with Arcane Orb from a distance: 
Sven, Underlord, 
Bristleback.
Additional:
* 
Arcane Orb's pure damage can do great damage to Underlord.
* 
Sanity's Eclipse can tear down Underlord's health by a large amount, since his mana pool is very low compare to OD's high mana pool.
Slardar
* Illusion heroes like the aforementioned 
Phantom Lancer or 
Naga Siren, or heroes that tend to buy 
Manta Style, like 
Luna or 
Juggernaut, will give Slardar a hard time, as his damage is single-targeted.
Underlord
* In general, heroes with spell immunity abilities won't be caught inside by Pit of Malice: Juggernaut, 
Lifestealer.
Underlord
* Heroes with abilities that can save teammates are also effective such as 
Shadow Demon, 
Dazzle, 
Oracle, 
Bane, 
Pugna, 
Tusk, 
Winter Wyvern, 
Io, Underlord, 
Treant Protector and 
Keeper of the Light.
Underlord
* Durable heroes relied a lot on their main passive effects and items' effects such as Bristleback, Underlord, 
Spectre and 
Dragon Knight can be disabled easily with 
Sharpshooter's break, reducing their potential in teamfights.
Underlord
* Heroes with long cast animations can be continuously interrupted by Battery Assault: 
Centaur Warrunner, 
Jakiro, 
Leshrac, Naga Siren, Underlord.
Slardar
* 
Tidehunter's 
Kraken Shell dispels Corrosive Haze and Bash of the Deep's stun if enough damage is taken. 
Anchor Smash and Kraken Shell's damage block also reduces Slardar's damage.
Underlord
* In general, heroes that provide vision will see Fiend's Gate coming: 
Techies, 
Templar Assassin, Treant Protector
Slardar
* Phantom Lancer's 
Doppelganger has a low cooldown and applies a basic dispel on PL, making it hard to keep Corrosive Haze on him.
* Phantom Lancer usually purchases Manta Style which provides another basic dispel to remove Corrosive Haze with.
* Besides Slithereen Crush, Slardar does not have another way to deal with illusions and has a low mana pool, which allows Phantom Lancer with 
Diffusal Blade to quickly build up illusions while draining Slardar's mana.
* 
Phantom Rush outruns Guardian Sprint, forcing Slardar to Blink away or use Slithereen Crush defensively to avoid being killed.
Underlord
* Heroes that require burst damage to kill will be difficult for Phantom Lancer to take down: 
Timbersaw, Axe, Bristleback, 
Alchemist and Underlord
Additional:
* Firestorm is very useful for clearing multiple illusions swiftly.
* Pit of Malice will continuously disrupt many illusions, drastically reducing their damage and potency.
* Athropy Aura reduces damage of both Phantom Lancer and his illusions.
Slardar
* With armor items like 
Solar Crest or 
Assault Cuirass combined with Bash of the Deep, Slardar can easily tank the 
Duel, If not dueled himself, he can drop Legion Commander's armor during duel and/or buff his teammate and save them, leaving her only the choice of dueling supports which can also be saved with fast Blink into Slithereen Crush.
Underlord
* Atrophy Aura's percentage-based damage reduction greatly diminishes Legion Commander's overall damage output, even if she has won many Duels
* Legion Commander cannot get out the way of Firestorm because she is stationary.
Additional:
* Atrophy Aura makes it hard for Legion Commander to win Duels.
* Fiend's Gate can be used to save Underlord and his allies from a Duel or to intercept Legion Commander, because outside from 
Overwhelming Odds, Legion Commander has no other area-of-effect abilities.
Slardar
* Corrosive Haze makes Riki completely vulnerable to Slardar and his allies, as Riki has no easy way of dispelling it.
* Slardar's physical damage with Slithereen Crush and Bash of the Deep amplified by Corrosive Haze can easily kill Riki.
Additional:
* 
Corrosive Haze works much like 
Track, giving the enemy team vision over Riki. While it doesn't give a movement speed or gold bonus, it instead can melt Riki's armor and Slardar can use 
Guardian Sprint to catch up to him.
* Slardar's Aghanim's Shard, causes 
Slithereen Crush to apply Corrosive Haze even if Slardar does not have vision over him.
Underlord
* Pit of Malice prevents Riki from casting 
Blink Strike. or 
Tricks of the Trade.
* Atrophy Aura reduces Riki's damage.
* Firestorm can be used to harrass Riki in lane.
Slardar
* Corrosive Haze followed by Slithereen Crush takes advantage of Alchemist's main weakness, being physical damage before he has the change to improve his surviability with items.
* 
Bash of the Deep will deal lots of damage during the laning phase.
Underlord
* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Fiend's GAte to get to a designated point of the map: 
Phantom Assassin, 
Terrorblade, 
Troll Warlord, 
Drow Ranger, Phantom Lancer, 
Chaos Knight, Sven, 
Wraith King, 
Bounty Hunter, Alchemist, Templar Assassin, 
Nyx Assassin, Bane.
Slardar
* Bounty Hunter's 
Shadow Walk is rendered useless with Corrosive Haze and makes Bounty Hunter an easy target for Slardar and his team.
Additional:
* Corrosive Haze provides True Sight on its target, exposing Bounty Hunter's position regardless of Shadow Walk.
* Guardian Sprint gives a very high movement speed bonus, allowing him to chase Bounty Hunter even if Slardar is tracked.
Underlord
* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Fiend's GAte to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, Bounty Hunter, Alchemist, Templar Assassin, Nyx Assassin, Bane.
Slardar
* Heroes who can provide True Sight or semi-reveal enemy heroes as Nature's Prophet is prone to buying 
Shadow Blade: Bounty Hunter, Slardar, Spectre, 
Zeus, Spirit Breaker.
Underlord
* Firestorm makes quick work of Treants and Atrophy Aura gives him temporary damage for every Treant killed.
* Pit of Malice can stop Teleportation channeling.
* Atrophy Aura greatly reduces Nature's Prophet's damage and he has no other good way to deal damage.
* Fiend's Gate can counter split-pushing, which is something that Nature's Prophet relies on a lot. Fiend's Gate can also be used to either escape from Nature's Prophet or to prepare an ambush on Nature's Prophet, and outside from Nature's Wrath, Nature's Prophet has no other ways to intercept arrivals with Fiend's Gate.
Slardar
* Slardar can attack through Plague Wards and gain Bash of the Deep charges, and Templar Assassin can spill 
Psi Blades through Plague Wards too.
Underlord
* 
Dark Rift allows Underlord to transport allies from poison damage-over-time to the fountain.
* Underlord usually buys 
Pipe of Insight that gives a magic resistance to allies, inhibiting the damage from Venomancer abilities.
Slardar
* Slardar can chase Dragon Knight down with Guardian Sprint and stun him with both Slithereen Crush and his passive Bash of the Deep. He can also use Corrosive Haze to whittle Dragon Knight's armor.
Underlord
* In general, heroes with long cooldowns on their abilities or ultimate will struggle against the relentless pressure provided by Dark Rift or Fiend's Gate (Requires 
Aghanim's Scepter): Terrorblade, Dragon Knight, 
Omniknight.
Slardar
* Slardar's level 25 talent makes Corrosive Haze undispellable, thus providing his allies vision of Slark.
Underlord
* Heroes with AoE abilities will hit Slark in Shadow Dance: 
Lina, Jakiro, Underlord, Leshrac, 
Dark Seer, 
Earthshaker, Timbersaw, 
Crystal Maiden.
Slardar
* Nyx Assassin's 
Vendetta can be revealed easily by Corrosive Haze
Additional:
* Corrosive Haze hinders Nyx Assassin's ganking attempts with Vendetta, as well as reducing his armor and make him very vulnerable due to his low health pool.
Underlord
* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Fiend's GAte to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, Bounty Hunter, Alchemist, Templar Assassin, Nyx Assassin, Bane.
Underlord
* Firestorm and Pit of Malice are very disruptive in team fights, completely matching Mars especially since it can all be cast inside Arena Of Blood and also does percentage-based magical damage, negating Bulwark.
* Dark Rift can save any allies of Underlord trapped in Arena Of Blood.
* Atrophy Aura allows Underlord to lane against Mars quite well since he does not have the best base damage during the early game.
* Underlord is a common carrier of both Pipe of Insight and 
Mekansm/
Guardian Greaves, allowing his team to combat Mars in the mid to late game.
Underlord
* Firestorm can deal serious damage to Phantom Assassin during laning.
* Pit of Malice prevents Phantom Assassin from either escaping or engaging with 
Phantom Strike.
* Phantom Assassin's damage output is entirely physical, therefore Atrophy Aura is very hazardous for her in most of the stages, particularly since it also affects 
Coup De Grace, hindering Phantom Assassin's main source of damage.
* Without proper items and any area-of-effect ability/item, Phantom Assassin cannot stop Underlord and his team to escape with Fiend's Gate, and she has nothing to intercept Underlord and his team when they use Fiend's Gate to teleport on any area of the map outside of 
Fan of Knives from Aghanim's Shard.
Additional:
* Pit of Malice prevents Phantom Assassin from either escaping or engaging with Phantom Strike.
* Phantom Assassin's damage output is entirely physical, therefore Atrophy Aura is very hazardous for her in most of the stages, particularly since it also affects Coup De Grace Coup de Grace, hindering Phantom Assassin's main source of damage.
* Without proper items and any area-of-effect ability/item, Phantom Assassin cannot stop Underlord and his team to escape with Fiend's Gate, nor she can intercept them if Underlord chooses to teleport on any area of the map.
Underlord
* In general, heroes that provide vision will see Fiend's Gate coming: Techies, Templar Assassin, Treant Protector
Slardar
* Heroes who can provide True Sight are always credible threats: Slardar, Bounty Hunter, especially Zeus since his 
Lightning Bolt provides True Sight without the need to detect her beforehand to apply the debuff. So even a late-coming Zeus can easily scout a large area to reveal her, and she cannot purge herself from his sight with the dispel talent.
Underlord
* Firestorm will destroy 
Refraction charges very quickly.
* Firestorm will hit Templar Assassin while under the effects of 
Meld Meld.
* Templar Assassin has a hard time maneuvering around Pit of Malice.
Underlord
* Atrophy Aura reduces Drow Ranger's damage significantly, as she relies on agility to be effective.
Slardar
* Low armor from Windranger's so the primary target use Corrosive Haze although her get Aghanim's Scepter, Windrun invisibility so useless and accessible by Slardar.
* Slardar's can easily catch her with combinating use Blink Dagger and Guardian Sprint also Slardar's can escaping avoided from Focus Fire.
Additional:
* Slardar always purchase Blink Dagger can combined Guardian Sprint will catch escaping her with 
Windrun and also avoided from 
Focus Fire after Slardar's sucessful stunned her with Slithereen Crush.
* Corrosive Haze from Slardar is very effective from low armor Windranger's although build Aghanim's Scepter, invisibility from Windrun is useless detected true sight against Corrosive Haze and can easily catch Slardar's kill her.
Slardar
* Corrosive Haze reveals Pudge's location, making it hard for him to use Meat Hook from the fog of war on Slardar's teammates or Slardar himself.
* Slithereen Crush interrupts Pudge while he is using Dismember.
* Guardian Sprint allows Slardar to avoid Meat Hook.
Additional:
* While Slardar has Guardian Sprint activated, 
Rot cannot slow him and 
Meat Hook is easier to avoid.
* Slithereen Crush allows Slardar to interrupt 
Dismember at close range (when Slardar is not a target).
* Corrosive Haze reveals Pudge's location, making it very difficult for him to land hooks from the fog.
Slardar
* The brutal physical damage of Slithereen Crush and Bash of the Deep can quickly remove Void Spirit's shield and stun him for a while.
* Corrosive Haze provides vision of Void Spirit while he is running away and Guardian Sprint allows Slardar to quickly close the gap
Slardar
* Guardian Sprint allows Slardar to outrun Bristleback, even when slowed by Viscous Nasal Goo.
* Corrosive Haze's armor reduction makes Bristleback much less tanky.
Slardar
* Weaver relies on 
Shukuchi to escape and kite enemy heroes. Slardar's Corrosive Haze lowers armor and reveals Weaver, who is already a very frail target.
* Weaver usually builds 
Linken's Sphere, Corrosive Haze can be used to pop the spell block, additionally the level 25 undispellable talent will prevent Weaver from removing Corrosive Haze with 
Time Lapse, allowing allied heroes to use their abilities on Weaver.
Additional:
* Corrosive Haze lowers armor and reveals Weaver during Shukuchi, who is already a frail target. In addition, Weaver usually builds Linken's Sphere, and Corrosive Haze can be used to "pop" the spell block. His level 25 talent can also make Corrosive Haze undispellable by Time Lapse, which puts Weaver in an even worse situation.
* Guardian Sprint can dodge Weaver's bugs with the movement speed bonus.
Underlord
* Pit of Malice is very good at preventing Primal Beast from entering the fight and stopping Trample damage at all stages of the game.
Underlord
* Pit of Malice can be cast in the path of Spirit Breaker's Charge of Darkness to cancel it.
* Fiend's Gate provides a way to escape from a gank for Underlord and his teammates. Likewise, Fiend's Gate can be used to ambush Spirit Breaker who has little to no ways of intercepting Underlod and his teammates when they use it to move around the map.
Underlord
* Atrophy Aura decreases Troll Warlord's damage.
* Pit of Malice helps lock down Troll Warlord.
* Battle Trance disallows Troll from running out of both Firestorm and Pit of Malice.
Slardar
* Clinkz survivability depends entirely on 
Skeleton Walk. Corrosive Haze not only makes its invisibility useless, but also makes Clinkz even more vulnerable to physical damage.
Additional:
* Slardar can reveal Clinkz with Corrosive Haze and make him easy to kill, and his Bash of the Deep also hits hard against Clinkz's naturally low health pool.
* Slardar's Guardian Sprint can catch up with Clinkz's Skeleton Walk.
* The stun and slow from Slardar's Slithereen Crush can hold Clinkz in place.
Slardar
* Slardar deals entirely physical damage. He does not have to worry about Counterspell.
* Slithereen Crush and Bash of the Deep prevent Anti-Mage from using Blink, the latter even if Anti-Mage activates Black King Bar.
* Corrosive Haze allows allies to take down Anti-Mage before he has a chance to Blink, and maintains vision over him even if he does Blink away.
Additional:
* Slithereen Crush and Bash of the Deep deals physical damage, bypassing the magic resistance bonus from 
Counterspell
* Corrosize Haze significantly increases the damage dealt against Anti-Mage, and makes it harder for him to flee with 
Blink, although Anti-mage can block its casting with with Counterspell
Slardar
* Corrosive Haze and Bash of the Deep will make short work of Huskar's low armor, even if Slardar is alone.
Underlord
* Firestorm will easily clear Chen's creeps.
* Pit of Malice will trap Chen and render him helpless.
* Atrophy Aura gives bonus damage to Underlord for each killed creep and weakens Chen's damage output.
* Fiend's Gate can counter Chen's pushing attempts, and he has nothing to intercept it.
Underlord
* Firestorm's percentage damage can quickly demolish the Spirit Bear's high HP
* Pit of Malice will allow allies to easily kite Lone Druid due to his low mobility
Underlord
* In general, melee heroes without blink mechanisms or spell immunity will have a hard time positioning against Pit of Malice: Sven, 
Tiny, Wraith King, Dragon Knight, 
Meepo, 
Doom, Bounty Hunter, Dark Seer, 
Undying, Alchemist, Legion Commander.
Underlord
* Heroes with powerful rooting abilities will disable most of Pangolier's skills, a bonus point if it pierces spell immunity since it will also be able to stop Pangolier during his Rolling Thunder: Treant Protector, Meepo, Crystal Maiden, 
Dark Willow, Underlord, Naga Siren
Underlord
* Underlord's Atrophy Aura reduces Morphling's high base damage gained through agility shift.
Slardar
* Crystal Maiden's already low armor and easily interruptible ultimate, 
Freezing Field can make Slardar her worst nightmare. Crystal Maiden also often builds 
Glimmer Cape which is revealed by Corrosive Haze.
Slardar
* Heroes with spells that negate invisibility such as Bounty Hunter, Zeus and Slardar prevent her from saving her allies with Moonlight Shadow.
Underlord
* In general, melee heroes without blink mechanisms or spell immunity will have a hard time positioning against Pit of Malice: Sven, Tiny, Wraith King, Dragon Knight, Meepo, Doom, Bounty Hunter, Dark Seer, Undying, Alchemist, Legion Commander.
Slardar
* 
Invoker's 
Ghost Walk can be countered, however, Invoker could also use abilities like 
Tornado or 
Ice Wall to escape by other means.
Underlord
* In general, heroes with long cooldowns on their abilities or ultimate will struggle against the relentless pressure provided by Dark Rift or Fiend's Gate (Requires Aghanim's Scepter): Terrorblade, Dragon Knight, Omniknight.
Underlord
* Heroes that reduce the damage that Marci can deal during her ultimate, like 
Razor, 
Rubick, Bane, Dragon Knight and Underlord.
Underlord
* In general, melee heroes without blink mechanisms or spell immunity will have a hard time positioning against Pit of Malice: Sven, Tiny, Wraith King, Dragon Knight, Meepo, Doom, Bounty Hunter, Dark Seer, Undying, Alchemist, Legion Commander.
Underlord
* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Fiend's GAte to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, Bounty Hunter, Alchemist, Templar Assassin, Nyx Assassin, Bane.
Slardar
* Slardar's Slithereen Crush allows him to stun Spectre and illusions, and Corrosive Haze prevents her from juking with 
Spectral Dagger.
Underlord
* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Fiend's GAte to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, Bounty Hunter, Alchemist, Templar Assassin, Nyx Assassin, Bane.
Slardar
* Heroes with armor reducing abilities greatly hinder Visage's defense like Slardar and Dazzle.
Slardar
* Terrorblade starts out with and gains a lot of armor from his agility growth. His illusions also make it difficult for Slardar to focus down the real Terrorblade.
Underlord
* Atrophy Aura reduces Terrorblade's damage significantly, even during Metamorphosis.
* Firestorm deals significant damage to Terrorblade and his illusions from a safe distance.
* Pit of Malice can keep Terrorblade and his illusions under control.
* Fiend's Gate can either bail out Underlord's team away from a bad engagement against a Terrorblade under Metamorphosis or caught Terrorblade off guard if he is not careful, and besides 
Reflection, Terrorblade has no other abilities to intercept Underlord nor his team when they use it to start a teamfight.
* Likewise, Fiend's Gate can be used to quickly move Underlord's team to the frontlines, to strike Terrorblade and his allies during Metamorphosis's 150 seconds of cooldown.
Additional:
* Firestorm deals significant damage to Terrorblade and his illusions from a safe distance.
* Pit of Malice can keep Terrorblade and his illusions under control.
* Atrophy Aura reduces Terrorblade's damage significantly, even during Metamorphosis.
* Fiend's Gate can either bail out Underlord's team away from a bad engagement against a Terrorblade under Metamorphosis or caught Terrorblade off guard if he is not careful, and besides Reflection, Terrorblade has no other abilities to intercept Underlord nor his team when they use it to start a teamfight. Likewise, Fiend's Gate can be used to quickly move Underlord's team to the frontlines, to strike Terrorblade and his allies during Metamorphosis's 150 seconds of cooldown, forcing Terrorblade to buy Aghanim's Scepter that will give him access to 
Terror Wave ability.
Underlord
* Melee heroes who may struggle to get close to Sniper: Wraith King, 
Kunkka, Doom, Tidehunter, Underlord, Troll Warlord, and etc.
Additional:
* Sniper's very long range allows him to stay out of Firestorm and Pit of Malice as well as Atrophy Aura range.
Slardar
* Slardar can use Guardian Sprint with Blink Dagger or Shadow Blade to get close, and Slithereen Crush will stun Sniper and slow him, making him vulnerable to Slardar's teammates.
* Corrosive Haze lowers Sniper's armor and makes Sniper's Shadow Blade useless, easily killing him with a few attacks.
Slardar
* 
Bloodseeker's 
Rupture forces Slardar to stay still during fights, preventing Slardar from using Guardian sprint to move in and out of fights. This takes away the ability to initiate and re-initiate with Slithereen Crush's low cooldown. Due to the increased move speed from Guardian Sprint, Slardar can lose health at about 160% the rate of normal heroes while under Rupture. Bloodseeker's 
Thirst also gives him enough move speed so that he's one of the few heroes who can outrun or catch up to a Slardar during Guardian Sprint.
Underlord
* Damage reduction from Atrophy Aura prevents Bloodseeker from killing targets and gaining his Thirst bonuses.
* Pit of Malice's area of effect catches Bloodseeker easily, negating his speed bonus during teamfights.
* Dark Rift allows Underlord to transport Ruptured allies to the fountain, rendering it useless.
Underlord
* In general, heroes that provide vision will see Fiend's Gate coming: Techies, Templar Assassin, Treant Protector
Slardar
* Corrosive Haze will reveal Treant Protector even when he is under the effects of Nature's Guise.
Slardar
* Slardar does not do well against multiple targets, as his only way to damage multiple targets is Slithereen Crush.
* Meepo's 
Earthbind will root Slardar, making him unable to chase/escape for the time being. Also, 
Poof's low cooldown and high damage can burst Slardar down rather quickly.
Slardar
* Heroes who can stun multiple units at once: Dark Willow, Spirit Breaker, Slardar, Invoker, and Tidehunter.
Underlord
* In general, melee heroes without blink mechanisms or spell immunity will have a hard time positioning against Pit of Malice: Sven, Tiny, Wraith King, Dragon Knight, Meepo, Doom, Bounty Hunter, Dark Seer, Undying, Alchemist, Legion Commander.
Underlord
* 
Doom with the {ValueColor:1|Doom applies Break|25tal} {Symbol:Talent} talent can be useful against heroes with troublesome passive skills while also disabling them for a long time: Phantom Assassin, 
Enchantress, 
Huskar, Underlord.
Additional:
* 
Infernal Blade does damage based on percentage health, and is useful against high health pool hero like Underlord.
* Doom can prevent Underlord from spamming his abilities and most important is to prevent him from using Fiend's Gate to escape.
Underlord
* In general, melee heroes without blink mechanisms or spell immunity will have a hard time positioning against Pit of Malice: Sven, Tiny, Wraith King, Dragon Knight, Meepo, Doom, Bounty Hunter, Dark Seer, Undying, Alchemist, Legion Commander.
Underlord
* Strong laners are usually at a disadvantage because of how well Sven can jungle. Heroes such as Dark Seer. Underlord and Legion Commander may find that later Sven takes care of them very quickly after some jungle farming.
Underlord
* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Fiend's GAte to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, Bounty Hunter, Alchemist, Templar Assassin, Nyx Assassin, Bane.
Slardar
* 
Medusa cares less than other heroes about armor reduction, since 
Mana Shield blocks 70% of all damage without taking armor/magic resistance into consideration. This makes 60% of your Corrosive Haze ineffective until Medusa's mana is drained.
Slardar
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.
Underlord
* Shadow Fiend can still dish out heavy damage with 
Requiem of Souls and 
Shadowraze while caught in Pit of Malice.
Slardar
* Shadow Fiend, a normal Shadow Blade builder often relies on its invisibility to escape fights. Corrosive Haze reveals Shadow Fiend and also weakens his already low armor.
Underlord
* 
Fury Swipes damage is not reduced by Atrophy Aura, essentially bypassing Underlord's only natural defense.
* 
Enrage can quickly dispel the root of Pit of Malice.
Slardar
* Slardar is one of the few meele heroes who can lane against Ursa in the early game, out harassing him with Bash of the Deep, and running away from a bad engagement with Guardian Sprint
* Corrosize Haze can force Ursa to cast Enrage defensively instead of offensively
* With Corrosize Haze, Slardar's team can quickly dispatch of Roshan, denying one of Ursa's greatest advantages
Underlord
* In general, heroes with spell immunity abilities won't be caught inside by Pit of Malice: Juggernaut, Lifestealer.
Slardar
* Heroes with high physical damage can damage Lifestealer more than he can heal: Bristleback, 
Clinkz, Luna,
Shadow Fiend, Slardar, Terrorblade
Underlord
* Heroes that depend on disrupting fights with ability combos or big ultimate abilities are vulnerable to the long stun of Fiend's Grip: 
Disruptor, 
Death Prophet, 
Enigma, 
Faceless Void, Invoker, 
Lich, 
Magnus, 
Mars, Medusa, 
Outworld Destroyer, 
Phoenix, Puck, 
Queen of Pain, Shadow Fiend, Treant Protector, Underlord, Winter Wyvern, 
Witch Doctor, Zeus.
Underlord
* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Fiend's GAte to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, Bounty Hunter, Alchemist, Templar Assassin, Nyx Assassin, Bane.
Slardar
* Illusion heroes like the aforementioned Phantom Lancer or Naga Siren, or heroes that tend to buy Manta Style, like Luna or Juggernaut, will give Slardar a hard time, as his damage is single-targeted.
Underlord
* Heroes with AoE nukes will clear her illusions in no time, especially if they are percentage-damage-based, like Underlord's Firestorm, 
Elder Titan's 
Earth Splitter, Enigma's Midnight Pulse, Zeus's 
Arc Lightning, Jakiro's 
Liquid Frost from Aghanim's Shard etc.
Slardar
* Illusion heroes like the aforementioned
Phantom Lancer or 
Naga Siren, or heroes that tend to buy 
Manta Style, like 
Luna or 
Juggernaut, will give Slardar a hard time, as his damage is single-targeted.
Underlord
*
Lunar Blessing gives allies bonus damage and armor required to endure against Atrophy Aura early on.
Eclipse can be devastating for Underlord's team when they're grouped up for Fiend's Gate, it can also be used to intercept arrivals with Fiend's Gate. And Pit of Malice does not prevent Luna to use it.
Aghanim's Scepter upgraded 
Eclipse can finish off Underlord or any of his teammates escape attempts with Fiend's Gate if timed correctly.
Lunar Blessing gives allies bonus damage required to endure against Atrophy Aura early on.
Eclipse can be devastating for Underlord's team when they're grouped up for Fiend's Gate, it can also be used to intercept arrivals with Fiend's Gate. And Pit of Malice does not prevent Luna from using it.
Aghanim's Scepter upgraded 
Eclipse can finish off Underlord or any of his teammates escape attempts with Fiend's Gate if timed correctly.
*
* To make things even better,
Additional:
*
*
* To make things even worse,