Dark Seer
* A Sniper who is somewhat competent at positioning is hardly going to be affected by any of Dark Seer's spells thanks to 
Take Aim.
* However, an illusion of Sniper made with Wall of Replica is extremely powerful, and hard to deal with.
Undying
* Sniper can easily destroy 
Tombstone from long range.
Dark Seer
* 
Spell Steal will easily steal all abilities from Dark Seer.
Additional:
* Spell Steal can perfect from Rubick's steal all abilities from Dark Seer. Rubick's always purchase 
Aghanim's Scepter can two stolens abilities from Dark Seer's and waiting for seconds for second stolen abilities (example: combinated Vacuum and Wall of Replica) and many different combination.
* A good positoning from Rubick's Spell Steal waiting steal abilities from Dark Seer 
Wall of Replica and illusion from Wall of Replica Dark Seer's can fighting with effect from outcome steal Wall of Replica from Rubick's.
* Combinated Rubick's steal 
Surge and 
Blink Dagger is very important catch from Dark Seer's and enemies.
* Rubick's 
Telekinesis can lifted up Dark Seer or enemy heroes and throw to Wall of Replica from Rubick's steal.
Undying
* All abilities from Undying easy to steal to Rubick with Spell Steal.
Additional:
* Tombstone can be stolen to counter-initiate the enemy team in skirmishes.
* Tombstone provides vision over the enemy around, use this to Rubick's advantage for more spells.
* Since 
Undying is melee and has low attack speed, the tombstone can be hard to taken down by Undying himself.
* 
Flesh Golem provides Rubick with increased Health pool and a powerful attack modifier.
* 
Rubick can apply the Flesh Golem debuff much more easily as a ranged hero.
* 
Decay is a decent damaging ability, making Rubick somewhat tankier in teamfights.
* 
Soul Rip can be used for extra heal or burst damage.
Dark Seer
* Dark Seer's only disable is Vacuum. Though he starts off with high armor and health, he'll eventually have a hard time dealing with high mobility heroes such as 
Weaver or 
Queen of Pain.
Undying
* Geminate Attack works on Tombstone, allowing Weaver to kill it quickly.
* Zombies attacking Weaver disappear once he goes invisible with Shukuchi.
* Undying has no way to catch a mobile Weaver.
Dark Seer
* 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.
Undying
* 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.
Dark Seer
* 
X Marks the Spot prevents Dark Seer or his allies from escaping with Surge.
Dark Seer
* 
Fortune's End dispels Ion Shell and Surge, making any gank attempt on Dark Seer in the laning phase likely to succeed.
* 
Fate's Edict prevents all magical damage that comes from Dark Seer's abilities.
* Fortune's End dispels Ion Shell on creeps, which Dark Seer relies on to farm and zone.
Additional:
* Fortune's End can dispel 
Ion Shell, a skill that helps Dark Seer immensely in the laning phase, as well as Surge, a move-speed buff, effectively allowing Oracle to control Dark Seer, especially in the laning phase.
Undying
* Due to Fervor and Battle Trance, Troll Warlord has a significant attack speed, enabling him to crush Tombstone quickly.
* Undying usually stays at the front line with no disables, making him an easy target for Troll Warlord.
Undying
* Necrophos is a dangerous opponent to go against with. Regardless of how much strength Undying has gained from Decay, Necrophos can finish off Undying with 
Reaper's Scythe once Undying's HP falls below a certain threshold.
* 
Heartstopper Aura will do more damage to Undying if he gained strength from Decay, as it does damage based on a hero's maximum health.
Undying
* Luna's 
Moon Glaives and 
Lunar Blessing can help her destroy Tombstone easily, and this becomes more effective if Luna is equipped with 
Manta Style.
* Spell Immunity of Zombies from Tombstone is a total disadvantage against Luna because 
Eclipse will strike only Undying, which can turn Undying's own ability against him.
* Though Undying often builds 
Blade Mail which can turn Luna's burst damage against her, Luna often builds 
Black King Bar which will allow her to attack Undying freely because Blade Mail cannot pierce spell immunity.
Additional:
* Luna's Moon Glaives and Lunar Blessing can help her destroy Tombstone easily, and this becomes more effective if Luna is equipped with Manta Style.
* Spell Immunity of Zombies from Tombstone is a total disadvantage against Luna because Eclipse will strike only Undying, which can turn Undying's own ability against him.
* Though Undying often builds Blade Mail which can turn Luna's burst damage against her, Luna often builds Black King Bar which will allow her to attack Undying freely because Blade Mail cannot pierce spell immunity.
Undying
* Zombies summoned from Tombstone will amplify the damage of 
Echo Slam due to them increasing the echo damage.
Undying
* 
Arcane Curse can effectively discourage Undying from casting his spammable abilities in a team fight, as Undying will have to suffer more damage and the slow due to the penalty duration of Arcane Curse.
* 
Last Word and 
Global Silence are able to silence Undying for up to 6 seconds, preventing Undying from gaining strength and healing his ally or himself.
Undying
* Flak Cannon rips through Tombstone's zombies.
Additional:
* 
Flak Cannon enables Gyrocopter to clear the zombies easily.
Undying
* Chemical Rage will take down Tombstone in no time.
Additional:
* With 
Greevil's Greed, Alchemist can farm Tombstone zombies and gain a significant gold advantage.
Dark Seer
* The constant dispel from Demonic Purge will make any attempt to save the victim or himself by Surge become futile. For what it's worth, Demonic Purge will also dispel Ion Shell.
Undying
* Tidehunter takes close to no damage from Undying's zombies once he maxes out his 
Kraken Shell, especially if he gets the level 20 Kraken Shell upgrading talent. This might allow him to blink away to safety.
Undying
* Split Shot can destroy Tombstone Zombies and Tombstone itself while still damaging heroes.
Dark Seer
* 
Flame Guard makes Dark Seer not deal any damage with his skills to Ember Spirit.
Undying
* 
Huskar's huge damage output and attack speed can get rid of Undying and Tombstone quickly.
Undying
* 
Invoker's multiple spells can lock down Undying and disable him from doing much.
Dark Seer
* Heroes with fast movement abilities will suffer huge damage when afflicted by Rupture: 
Spirit Breaker, 
Earth Spirit, Dark Seer.
Additional:
* 
Rupture can deal a lot of damage to either a surged Dark Seer or his allies and prevent the target from getting into position.
Dark Seer
* Dark Seer's only disable is Vacuum. Though he starts off with high armor and health, he'll eventually have a hard time dealing with high mobility heroes such as Weaver or Queen of Pain.
Undying
* 
Death Prophet is able to 
Silence Undying up to 6 seconds. Besides, due to Undying's high strength during a team fight, 
Spirit Siphon is a powerful ability against Undying thanks to the percentage health drain.
Undying
* 
Mirana can destroy Tombstone, and evade zombies using Leap and Moonlight Shadow's invisibility.
Dark Seer
* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as 
Disruptor's 
Kinetic Field or 
Slark's 
Pounce.
Dark Seer
* In general, heroes who are melee with no way to fight back can be very easily poked by Monkey King to gain his Jingu Mastery stacks: Dark Seer, 
Riki, Rubick.
Undying
* Heroes with summons that are destroyed by a fixed number of attacks: Undying's Tombstone, 
Gyrocopter's 
Homing Missile, and 
Zeus's 
Nimbus.
Undying
* 
Reactive Armor makes Timbersaw very effective against heroes that control a lot of units, such as 
Broodmother, 
Lycan and Undying.
Undying
* Lifestealer is able to endure Undying, especially in the laning phase, where Undying is strongest. Feast can offset Decay's strength steal for its percentage lifesteal. Rage delays Undying from stealing strength and can help Lifestealer destroy Undying's Tombstone uninterrupted. As well, none of Undying's abilities pierce magic immunity.
Dark Seer
* Heroes with escape abilities : 
Anti-Mage Dark Seer Slark 
Storm Spirit 
Windranger Weaver can kite Lifestealer due to him having no lockdown
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: 
Beastmaster, Broodmother, 
Enigma, 
Nature's Prophet, 
Visage, 
Warlock, Wraith King.
Undying
* Undying's Tombstone will cheerfully chew through treants, incidentally netting you some extra income during fights.
* The above interaction tends to ensure that skirmishes are heavily populated with units, thereby buffing Soul Rip
Dark Seer
* Dark Seer can pull together Spectre's illusions with 
Vacuum, and Wall of Replica creates an illusion of Spectre that deals massive damage.
Undying
* Spectre must chase for kills and relies on movement speed for mobility in fights, and has no way to counter the Tombstone zombies.
* The potency of Soul Rip can be increased from nearby illusions from Haunt.
* Decay will shut down Spectre during the laning phase by effectively cutting down her initial health pool.
Additional:
* Spectre must chase for kills and relies on movement speed for mobility in fights, and has no way to counter the Tombstone zombies.
* The potency of Soul Rip can be increased from nearby illusions, so Undying can use 
Haunt against Spectre.
* Early game Decay will make Spectre easy to shut down in lane.
Undying
* Decay, Soul Rip and Flesh Golem all deal magical damage which ignores Bulwark.
* Decay reduces Mars' natural strength and therefore his health pool, which is what he relies on to trade effectively in lane.
Dark Seer
* Ion Shell destroys 
Refraction's protection stacks in short time.
* Surge ignores the massive slow from 
Psionic Trap.
Undying
* Undying's Decay is a dangerous ability against Bristleback, as it makes him more vulnerable and reduces his tankiness.
* Undying's Tombstone together with Flesh Golem can slow Bristleback down significantly.
Undying
* Due to Spirit Breaker's low attack speed, Tombstone is problematic for Spirit Breaker as the zombies summoned from Tombstone apply a stacking movement speed slow, which can significantly reduce Greater Bash's damage.
* Soul Rip and Decay allows Undying and his allies to survive and recover from any incoming ganks by Spirit Breaker.
Undying
* Undying saps strength from heroes with Decay, and Ogre Magi's high strength gain will allow Undying to steal more and more strength, becoming stronger with each use.
* Due to the Strength steal from Decay, Undying is normally very tanky, and has high health, making it harder for Ogre Magi to kill him.
Dark Seer
* Surge allows for Dark Seer and his allies to escape from Upheaval due to it ignoring any slow.
Undying
* Decay can be good against Centaur Warrunner, as reducing the health of Centaur can make 
Double Edge risky.
* His zombies do not proc 
Retaliate, as it only procs for regular attacks.
Undying
* Winter Wyvern cannot handle the Zombies created by Undying's Tombstone very well. In most situations, Zombies will have more movement speed than her.
* Undying can gain one or two easy Decay stacks on an ally in Cold Embrace. The ally will still take the damage as well.
Additional:
* Winter Wyvern cannot handle the Zombies created by Tombstone very well. In most situations, Zombies will have more movement speed than her.
* Undying can gain one or two easy Decay stacks on an ally in Cold Embrace. The ally will still take the damage as well, since it is magical.
Dark Seer
* Venomancer is a low health hero and low range hero who is easy to harass with Ion Shell on a creep in the early game.
* Venomancer depends entirely on all his slows to keep distance or chase, but since Surge ignores slows, it is nearly impossible for Venomancer to hunt or run away from Dark Seer or his surged teammates.
Dark Seer
* Ion Shell is a very powerful weapon against Broodmother's Spiderlings and makes her laning much harder.
Additional:
* Ion Shell zones out Broodmother in the laning phase, and can kill her spiderlings if used on one Spiderling in a group.
* Vacuum can pull Broodmother out of the treeline.
Dark Seer
* Dark Seer's Vacuum and Ion Shell can clear a wave of Chen's Creeps effectively.
* Surge applies haste movement and negates the slow from 
Penitence, allowing Dark Seer to easily escape from Chen and his creeps.
* Dark Seer's full combo from Dark Seer's Vacuum, Wall of Replica and 
Normal Punch from Aghanim's Scepter can often kill Chen or any of his allies before he can save them with 
Hand of God.
Additional:
* Dark Seer's Vacuum and Ion Shell can clear a wave of Chen's Creeps effectively.
* Surge applies haste movement and negates the slow from Penitence, allowing Dark Seer to easily escape from Chen and his creeps.
* Dark Seer's full combo from Dark Seer's Vacuum, Wall of Replica and Normal Punch from Aghanim's Scepter can often kill Chen or any of his allies before he can save them with Hand of God.
Dark Seer
* 
Living Armor can be destroyed quickly with Ion Shell.
Dark Seer
* Heroes with haste can negate Enchant's slow: Weaver, Dark Seer, Lycan, 
Centaur Warrunner.
Undying
* Heroes with a slow attack rate will find themselves struggling to take out Tombstone, like Doom.
Dark Seer
* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): 
Vengeful Spirit, 
Keeper of the Light, Huskar, Dark Seer
Dark Seer
* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: 
Phantom Assassin, Windranger, 
Hoodwink.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Dark Seer
* Dark Seer can increase the movement speed of allies with Surge, breaking Static Link.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Undying
* Generally, any fragile heroes will have a hard time dealing with Undying's tankiness, and even more so if Decay is used on them. Some examples are 
Crystal Maiden and 
Witch Doctor.
Dark Seer
* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.
Dark Seer
* Heroes with hastes: Dark Seer, Lycan
Dark Seer
* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.
Dark Seer
* Heroes who do not have nor rely on passive abilities make Nethertoxin much less effective: 
Clinkz, 
Pugna, Nature's Prophet, Dark Seer, Lycan, 
Tusk
Dark Seer
* The haste provided by Dark Seer's Surge or a {Rune:Haste} renders your slows ineffective.
Dark Seer
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: 
Venomancer, Huskar, 
Ember Spirit, Dark Seer, 
Sand King, Doom, 
Dawnbreaker. However, this also means they are easily stunned.
Dark Seer
* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: 
Phantom Lancer, 
Chaos Knight, 
Naga Siren, 
Terrorblade.
Undying
* Generally, any fragile heroes will have a hard time dealing with Undying's tankiness, and even more so if Decay is used on them. Some examples are Crystal Maiden and Witch Doctor.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Undying
* Terrorblade can destroy Tombstone with his 
Conjure Image and 
Metamorphosis.
Dark Seer
* Dark Seer's Vacuum and Ion Shell allows him to clear a wave of Terrorblade's illusions.
* Because Terrorblade often builds items that require 
Ultimate Orb like Manta Style and 
Eye of Skadi, Dark Seer can create a very strong illusion of Terrorblade with Wall of Replica and Normal Punch from Aghanim's Scepter.
* If Dark Seer can use Vacuum to help teammates land their AoE abilities, Terrorblade will be quickly killed before he even gets a chance to use Sunder.
Additional:
* Dark Seer's Vacuum and Ion Shell allows him to clear a wave of Terrorblade's illusions.
* Because Terrorblade often builds items that require Ultimate Orb like Manta Style and Eye of Skadi, Dark Seer can create a very strong illusion of Terrorblade with Wall of Replica and Normal Punch from Aghanim's Scepter.
* If Dark Seer can use Vacuum to help teammates land their AoE abilities, Terrorblade will be quickly killed before he even gets a chance to use Sunder.
Dark Seer
* 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.
Undying
* Undying can use Decay not only to reduce Sven's maximum health, but also to reduce the damage he can deal with his ultimate.
* Zombies spawned by Tombstone together with Flesh Golem slow Sven down significantly. Landing Sven's powerful but somewhat slow right-click on Tombstone would be a waste.
Undying
* Meepo can quickly destroy Tombstone thanks to 
Divided We Stand.
Dark Seer
* Dark Seer can take great advantage of Divided We Stand by putting an Ion Shell on a clone in order to harass them effectively.
* Vacuum can take a single Meepo and disable him for Dark Seer and his teammates to take out.
Dark Seer
* Abilities that deal low damage with high amounts of instances are irrelevant against Pudge during Flesh Heap's active: Gyrocopter's 
Rocket Barrage and Dark Seer's Ion Shell are just a couple examples.
Undying
* Anti-Tank heroes like: 
Razor, 
Necrophos, Undying.
Dark Seer
* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as Disruptor's Kinetic Field or Slark's Pounce.
Dark Seer
* Heroes with AoE abilities will hit Slark in Shadow Dance: 
Lina, 
Jakiro, Underlord, 
Leshrac, Dark Seer, 
Earthshaker, 
Timbersaw, Crystal Maiden.
Undying
* Phantom Lancer's many illusions will easily destroy Tombstone, provided he has sufficient farm.
* He also has no ways of dealing with the illusions, since Decay doesn't steal strength from illusions.
Dark Seer
* Ion Shell helps taking down illusions quickly, making it easy to identify the real Phantom Lancer.
* Surge allows Dark Seer and his teammates to run away from Phantom Lancer, who relies on his 
Phantom Rush to chase enemies.
Undying
* Chaos Knight's multiple illusions from 
Phantasm can destroy Undying, as Soul Rip can't offset the damage from the high amount of damage from his illusions.
Dark Seer
* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.
Undying
* Familiars will easily be able to kite heroes with a short range or with low attack speed. For example, Tiny and Undying have a very hard time killing Familiars.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Dark Seer
* Dark Seer's strength lies in his high-mana cost skills. So
Mana Break can be a great nuisance for him, since it can reduce his mana and prevent him from casting his spells.
Mana Void can deal a lot of damage if Dark Seer spent a lot of mana on his abilities.
*
Undying
*
Tombstone's zombies rarely inhibit Anti-Mage, as he can either Blink away or onto the Tombstone and destroy it.