* 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.

* Rubick can steal Death Ward easily as it is a channeled ability and then use it to turn teamfight to his advantage.
* However, a skilled Witch Doctor will toggle Voodoo Restoration immediately after placing his Death Ward to prevent that.

* Rubick's ability to steal Attribute Shift (Strength Gain) makes him extremely annoying to deal with because Rubick's shifted attributes will remain even if he steals a new spell.
* If Rubick moves enough points to strength and then steals Adaptive Strike, he will have a powerful 3-second ranged stun in his arsenal as well.
* Waveform provides a reliable nuke/escape to Rubick.
* Rubick can steal most abilities Morphling uses while Morphed, allowing Rubick to steal his own allies' abilities if the Morphling is not careful.

* All of Lion's abilities are worth stealing with Spell Steal.
* Arcane Supremacy makes the disabling spells stolen from Lion very useful, allowing you to disable enemies for an extremely long time during fights or ganks.
* By using Telekinesis, Rubick can easily catch Lion out. Without any escape mechanism, Lion is helpless, especially when ganked.

* 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.

* 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 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.

* Burrowstrike is one of the best and easiest steals for Rubick and Sand King should be careful when playing against him - it's much better to give away Sand Storm.

* 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.

* If Rubick can use Spell Steal to take Nethertoxin, he will be able to disable Corrosive Skin, reducing much of Viper's durability.
* He can also steal Viper Strike, which can be used to hinder a hero on your team (or multiple heroes, if Rubick has Aghanim's Scepter).

* 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.

* 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.

* Telekinesis has a longer range than the AoE of Black Hole for the purposes of cancelling it.
* All of Enigma's spells are useful to Spell Steal.
* Malefice is useful for interrupting channeling spells or long cast animations. Its stun duration is also amplified thanks to Spell Steal's debuff amplification.
* Demonic Conversion can be used to push or counter-push a lane.
* Midnight Pulse is useful to block an area or for team fights.
* Black Hole is very easy to steal, as it is a channeled ability. It's also one of the best ultimate abilities for team fights, and it can easily turn the fight around for the enemy team. It also does more damage and has a larger cast range thanks to Arcane Supremacy. A stolen Black Hole can also cancel Enigma's Black Hole.

* Fiend's Grip is a powerful but channeled ability, making it useful and easy to Spell Steal and interrupt with Telekinesis.
* Stolen Fiend's Grip or Nightmare combined with Arcane Supremacy allows Rubick to disable Bane's allies for a longer period of time.
* As a natural Aghanim's Scepter carrier, Rubick can steal an upgraded Fiend's Grip and deal lots of damage to Bane's allies.

* Rubick can use Spell Steal to steal Astral Imprisonment, and if Rubick gets Aghanim's Scepter he gets 2 charges of it. This can overpower Outworld Destroyer in team fights.
* Rubick can also steal Sanity's Eclipse against Outworld Destroyer's teammates.

* Fade Bolt can hinder Jakiro's early pushing power by clearing creep waves.
* All of Jakiro's spells are great for Rubick to Spell Steal.
* Ice Path is a great spell for Rubick so steal, since Rubick has no cast time on stolen abilities, making Rubick's version of Ice Path much more reliable than Jakiro's.
* Macropyre is a great way for Rubick to farm.

* Rubick is a potential counter to Bounty Hunter as he can steal his Track and use it against his invisibility, and also provide his team with more gold if the tracked hero is killed.

* All of Venomancer's abilities are decent choices for Rubick's Spell Steal. Stealing Plague Wards makes them apply Poison Sting as well.

* All of Vengeful Spirit abilities are very good for Rubick to Spell Steal:
* Magic Missile provides an additional nuke/disable to pair with Fade Bolt and Telekinesis, respectively.
* Wave of Terror serves as a good scouting/armor reduction skill that Rubick and his team can benefit from.
* Nether Swap complements Rubick's mobility and pairs well with other mobility items he usually builds. He can also use it to save an ally from danger.

* All of Magnus's spells are perfect for Rubick to steal, especially Reverse Polarity for a counter-initiation.
* Telekinesis is one of the best instant-disables in the game, completely ruining Magnus's initiation.

* 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.

* All of Treant Protector's abilities are worth stealing, and Rubick is able to cast them with no animation time.

* All of Omniknight's abilities are valuable for Rubick to Spell Steal, and Omniknight has no throwaway ability to cover his last used spell.

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

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

* All of Underlord's abilities are useful for Rubick to Spell Steal.

* 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.

* Heroes that reduce the damage that Marci can deal during her ultimate, like Razor, Rubick, Bane, Dragon Knight and Underlord.

* If Rubick steals Reaper's Scythe, he can turn the powerful ultimate back against Necrophos's team. Even his other spells are useful in Rubick's hands, giving him a sustain or a weak initiation/protection tool.

* Fade Bolt reduces damage output of Anchor Smash.
* Ravage is an easy target to Spell Steal, so always be sure to use Anchor Smash immediately after Ravage when playing against a Rubick.
* Spells stolen by Rubick are potentially stronger due to the lack of cast animations, his talents, and his passive, Arcane Supremacy.

* 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.