* 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.

* 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.

* Venomancer has low health, which makes him vulnerable to Lina's heavy magic damage.
* Fiery Soul attack speed bonus removes Plague Wards easily in all stages of the game.

* Dragon Slave deals reliable magic damage during the laning phase against Mars.
* Lina's Eul's Scepter of Divinity and Light Strike Array combo can interrupt Mars from being disruptive for a decent amount of time and leave him vulnerable for follow up stuns.
* Laguna Blade deals massive magical damage, and pure damage with Aghanim's Scepter.

* Snowball can be used to save allies or himself during Venomous Gale and Poison Nova.
* Venomancer lacks mobility and has low base health, so he can be killed by Walrus PUNCH!

* Snowball can protect Tusk and his teammates from a Spear of Mars' stun after an Arena of Blood, and with proper targeting, even bring them out of the Arena. This is especially noticeable in the earlier stages of the game before allies buy Black King Bar and rely on this less. Even during the late-game, Tusk can purchase a Blink Dagger to save allies that are caught before Black King Bars can be used by Blinking in and Snowballing out.
* Tag Team is a constant threat to Mars in-lane, as it deals significant damage and slow, making Bulwark slightly ineffective.
* It is worth noting that Ice Shards can be detrimental to Tusk's own team by creating terrain that Spear of Mars can latch on, though using it conservatively is a good enough solution in most cases.

* Corrosive Skin means Viper can often outlast Venomancer in a battle of attrition.
* Venomancer has no mobility without items, which makes him vulnerable to constant slows.

* Nethertoxin breaks the damage block from Bulwark.
* Poison Attack and Viper Strike's slows make it difficult for Mars to contribute to fights due to his low mobility.
Additional:
* Nethertoxin disables Bulwark entirely, making Mars far less tanky. Using Nethertoxin inside Arena of Blood may discourage enemies from following up with Mars' initiation.
* Rod of Atos is currently common on Viper and keeps Mars in position long enough to be killed.
* Beware that Viper is not very tanky earlier in the game, so positioning against Mars is important since a well-timed Spear of Mars can be the end of Viper.

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, etc.

Additional:
* Huskar can easily regenerate lost health from DoT spells through Berserker's Blood rendering them ineffective
* Venomancer has little armor and mobility, and rarely builds Linken's Sphere, so he is quite vulnerable to Life Break.

* Burning Spear's magical damage is very troublesome for Mars in the laning stage.
* Life Break's percentage-based magical damage bypasses Bulwark, and can also be used to jump in or out of Arena Of Blood.

* Venomancer's damage-over-time abilities are easier to heal through with numerous Shadow Waves than other types of damage, and it's simple to time a Shallow Grave until the last possible second to save a teammate from them.

* Heroes that can save their allies can be a big problem for Mars: Dazzle, Omniknight.

* Squishy heroes or heroes without hard disables or silences: Shadow Demon, Shadow Fiend, Venomancer, Ancient Apparition etc.

* Ball Lightning makes it almost impossible to catch Storm Spirit without someone else initiating for you.
* Overload is not reduced by Bulwark and the magical damage spam can wear down Mars quickly.
Additional:
* Storm Spirit's abilities all do magical damage, which can bypass Bulwark.
* Ball Lightning can escape through Arena of Blood and it is easy to dodge Spear of Mars.

* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.

* Nether Blast, Decrepify and Life Drain deal high magical damage and bypasses Bulwark.
* Nether Ward reduces the amount of abilities Mars can use during fights and forces Mars to be careful about the heavy mana cost of Arena Of Blood.
* Pugna is one of few heroes that can contest Mars' ability to push and defend towers early on.

* In the laning stage, making illusions of Venomancer will turn his Poison Sting back at him, making for an easy gank at level one, and for later when your mid comes for ganks.

* Heroes with break abilities: Shadow Demon (with Aghanim's Scepter), Viper.

* Fortune's End and False Promise easily dispel many crippling debuffs, such as Venomancer's Venomous Gale, or Skywrath Mage's Ancient Seal.

Additional:
* Fortune's End can dispel Venomous Gale and Poison Sting from allies.
* Fate's Edict grants 100% magic resistance to target, inhibiting the damage from Venomancer abilities.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* 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.

* 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.

* Arcane Orb's pure damage ignores Mars' Bulwark.
* Astral Imprisonment can be used to stop Mars from being disruptive or save allies from his abilities.
* Sanity's Eclipse deals high damage to Mars, due to his low intelligence pool.

* Necrophos' largely magical damage completely ignores Bulwark.
* Ghost Shroud protects Necrophos from God's Rebuke but more importantly stops Mars from being a threat in lane.

* Mars' own father is a formidable foe because Zeus deals massive amounts of magical damage. The high damage, low cooldown nukes of Arc Lightning and Lightning Bolt combined with the percent health magic damage of Static Field will shred Mars' health because it bypasses Bulwark completely.

* Rage, acting as a pseudo-Black King Bar, completely negates Mars' initiation if used in time.
* Feast does damage and heals based on max health, perfect against high-health strength heroes like Mars.
* Infest allows Lifestealer to potentially save allies from Mars' initiation with a quick burst of extra health.

* While Reincarnation is off cooldown, Poison Nova poses less of a threat as Wraith King will return with all debuffs cleared.
* Vampiric Spirit can out-heal the slow {tooltip:DoT|Damage over Time} from Poison Sting.

* It is difficult for Mars to trade blows with Ogre Magi in the early game thanks to his high base health, resistance and Ignite.
* Bloodlust can assist Ogre Magi or an ally in repositioning against Mars for its move speed bonus.
* Fireblast can interrupt and mitigate Mars from performing his skill combos, especially in combination with Multicast.

* Voodoo Restoration heals to counter damage over time of Poison Nova and Poison Sting.

* Shadowraze deals magic damage and ignores Bulwark.
* Requiem of Souls deals magic damage and can fear Mars away, forcing him to turn around and therefore become vulnerable.

* Rebound allows her to jump in or out of the Arena Of Blood. She can save her allies from the Arena with Dispose as well.

* Swashbuckle is an auto attack and therefore ignores Mars' Bulwark.
* Shield Crash upgraded with Aghanim is an auto attack and therefore ignores Mars' Bulwark.
* Rolling Thunder makes him immune to magic, making Pangolier able to roll in and out of Mars' Arena Of Blood.

* Time Dilation while Spear of Mars and God's Rebuke are on cooldown will make these abilities unusable for a long time, rendering Mars nearly useless.
* Mars cannot turn inside the Chronosphere, which makes it easy to attack him from the back, bypassing Bulwark completely.
Additional:
* Time Walk allows Faceless Void to escape or enter Arena Of Blood, and helps him recover from Mars' burst damage.
* Time Lock's magical damage ignores Bulwark.
* Chronosphere allows Faceless Void to reposition behind Mars, ignoring his Bulwark while he is helplessly frozen in time.

* Venomous Gale is a great ganking and farming skill.
* Plague Ward serves as a flexible ability for pushing, ganking, farming and scouting. The innate Poison Sting also works on the stolen Plague Ward with half the damage.
* Poison Nova, if stolen and cast, puts a huge damage-over-time debuff on the enemy team, even greater than Venomancer himself with the help of Arcane Supremacy.
* Spell Steal has a greater cast distance than the effect area of Poison Nova, allowing Rubick to steal the spell while staying at the back.
* Venomancer suffers from mana pool problems, while Rubick has relatively high intelligence gain and can cast the same set of spells at ease.
Additional:
* All of Venomancer's abilities are decent choices for Rubick's Spell Steal. Stealing Plague Wards makes them apply Poison Sting as well.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Nukers who have set amounts of damage will really struggle against Lone Druid especially in True Form: Puck, Void Spirit, Mars.

* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.

* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.

* Ursa is a special mention because despite Bulwark diminishing most of the damage Ursa does, he is quite durable, especially with Enrage, discouraging the aggressive all-in playstyle of Mars; Ursa can simply not target Mars.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Heroes with high health especially Strength heroes will take more damage on Sun Ray: Axe, Pudge, Bristleback, Mars.

* Slardar can attack through Plague Wards and gain Bash of the Deep charges, and Templar Assassin can spill Psi Blades through Plague Wards too.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* 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.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Kunkka's Ghostship and Torrent disrupt fights in Arena Of Blood.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Heroes with damage-over-time abilities will not only proc Bristleback's passive continuously, they will also do little harm to him when he is facing away from the source: Venomancer, Arc Warden

* Blink Strike gives bonus backstab damage and can bypass Bulwark. Defensively, it could be used to teleport away from Mars, especially while inside Arena of Blood.
* Smoke Screen can interrupt Mars' skill combos, especially when cast inside Arena of Blood.
* Tricks of the Trade can be used to evade Mars' skills, which have a slight delay to them. It could also be used to buy himself time while trapped inside of Arena of Blood.
Additional:
* Bulwark is generally irrelevant against Riki as he primarily deals bonus damage from behind.

* Venomancer's damage-over-time abilities do little damage against Counterspell.
* Blink helps Anti-Mage get away from Venomancer's slows.
Additional:
* Counterspell provides magic resistance, diminishing the effectiveness of Venomancer's spells.
* Venomancer's lack of hard disable allows Anti-Mage to use Blink, circumventing the slows Venomancer depends on.

* Solar Guardian can save allies caught inside Arena of Blood

* Teleportation allows Natures Prophet to save himself from the damage over time of Venomous Gale, Poison Sting and Poison Nova.
* Plague Wards can be destroyed with Nature's Prophet's Treants.

* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, Earth Spirit, Ogre Magi

Additional:
* Press the Attack dispels Venomous Gale and Poison Sting from Legion Commander or her teammates.
* Venomancer is an ideal target for Duel due to his lack of mobility and low starting health.

* Legion Commander is both good and bad vs Mars, on the plus side she can dispel Spear of Mars with Press the Attack and is a good Silver Edge carrier. However, Mars is not an ideal Duel target, as Bulwark will force her to 1: Buy Silver Edge, and 2: Hit Mars with it before the Duel, allowing a skilled Mars to react, especially with Eul's Scepter of Divinity. In teamfights, Mars will happily draw attention after using his abilities, and tank the Duel with all spells on cooldown.