* Enigma's left level 25 talent (increasing the Eidolon count from three to eleven) powers up Undying's Soul Rip.

* Chaotic Offering's spell immunity piercing stun can stop Black Hole's channeling. Due to this ability's large area of effect, it can be cast at a safe distance from the Black Hole.
* Fatal Bonds can be used to make Enigma's Eidolons easier to kill, potentially feeding the enemy team.
* Warlock's Upheaval can interfere with Enigma's initiation and potential follow-ups thanks to its large AoE.
Additional:
* Chaotic Offering pierces spell immunity and is an area of effect ability, therefore it doesn't matter if Enigma buys Black King Bar or Linken's Sphere Warlock will always be able to cancel channeling of Black Hole.
* Enemies often get clumped up around Black Hole giving Warlock a perfect opportunity to cast Fatal Bonds and Upheaval on multiple enemies.

* 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.

* Channeling heroes will not go well against Warlock, especially those who build Black King Bar as Warlock's ultimate ability stun goes through spell immunity. E.g.: Crystal Maiden, Shadow Fiend, Enigma, etc.

* 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

* 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.

* Chaotic Offering can destroy the tree Monkey King is standing on.
* Shadow Word and Fatal Bonds constantly puts Tree Dance on cooldown.

* Decay can be good against Centaur Warrunner, as reducing the health of Centaur can make Double Edge risky.
* His zombies do not proc Return.

* Lacking escaping mechanisms, being dependent on fair positioning and channeling for his ultimate, its easier to Warlock with your long range crowd control abilities to lock the Shadow Fiend down to your team.

* 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.

* Decay's stacking strength reduction makes Axe much less dominant in lane.
* Tombstone's zombies take no damage from Counter Helix, and will continuously put Axe's Blink Dagger on cooldown until dealt with.

* 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.

* 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.

* 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.

* 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.

* Anti-Tank heroes like: Razor, Necrophos, Undying.

* While heroes with strong mobility able to get close/flee or long range disables do well against him, heroes with no escaping abilities/lacking long disables will perish against Warlock. Once the {U:Warlock Golem} lands with its stun, its hardly possible to escape when he casts Upheaval. Just watch your pet burn the enemies as they try running away or blow their strongest abilities to stop your {U:Warlock Golem}. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.

* While heroes with strong mobility able to get close/flee or long range disables do well against him, heroes with no escaping abilities/lacking long disables will perish against Warlock. Once the {U:Warlock Golem} lands with its stun, its hardly possible to escape when he casts Upheaval. Just watch your pet burn the enemies as they try running away or blow their strongest abilities to stop your {U:Warlock Golem}. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.

* Heroes with a slow attack rate will find themselves struggling to take out Tombstone, like Doom.

* Viper cannot interrupt heroes with powerful channeling abilities: Bane, Enigma, Shadow Shaman, Warlock

* While heroes with strong mobility able to get close/flee or long range disables do well against him, heroes with no escaping abilities/lacking long disables will perish against Warlock. Once the {U:Warlock Golem} lands with its stun, its hardly possible to escape when he casts Upheaval. Just watch your pet burn the enemies as they try running away or blow their strongest abilities to stop your {U:Warlock Golem}. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.

* Fatal Bonds links the Meepos together.

* Due to Spirit Breaker's low attack speed, Tombstone is problematic for Spirit Breaker.
* 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 from incoming ganks of Spirit Breaker.

* {U:Warlock Golem}s do plenty of physical and pure damage to bring down Huskar when he is at low health. Warlock is always a hazard for Huskar to initiate by using Life Break because Chaotic Offering can stun him instantly, even when Black King Bar is activated, and allow Warlock's team to gather their wit and retaliate.
* After jumping in, Huskar will not have any means to escape Upheaval. Being an attack-dependent hero, this is bad for him.

* Because Templar Assassin does not have escape potential in lane, any support hero with roaming potential and a Dust of Appearance can be great at shutting her down early game: Earth Spirit, Spirit Breaker, Tusk, Bounty Hunter, Riki, Warlock.

Additional:
* Warlock can cast Upheaval when Templar Assassin uses Meld, preventing escape.
* Warlock can also send his {U:Warlock Golem} near where she used Meld, preventing escape by Blink Dagger due to the {U:Warlock Golem} Permanent Immolation.

* 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.