* 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.

* Whirling Death deals damage as well while reducing 15% of Bristleback's strength, which reduces Bristleback's tankiness.
* Reactive Armor can sustain through multiple Viscous Nasal Goo and Quill Spray stacks.
* Timber Chain makes it hard for Bristleback to slow down Timbersaw with Viscous Nasal Goo.

* 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.

* Whirling Death reduces Axe's strength by 15%, making him much less tanky, especially in the early game. It is also stackable.
* Axe's Blade Mail is ineffective against attribute changes, and Timbersaw's mobility with Timber Chain means he can wait out Blade Mail's duration.
* Reactive Armor's armor and regeneration makes it much harder for Axe to finish Timbersaw with Culling Blade.
* Chakram disarms Timbersaw, making Counter Helix less effective.

* Timbersaw relies on dealing massive amounts of pure damage, making Cold Embrace a good setup for his nukes.
* If he has Reactive Armor stacks, Timbersaw can tank the damage from his allies if he is targeted by Winter's Curse. If he's not the target, Timbersaw's abysmal attack damage will contribute next to nothing when he is cursed to attack an ally.

* 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'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

* Heroes that have AoE damage: Lina, Keeper of the Light, Timbersaw, Leshrac, Bristleback, Axe

Additional:
* Timbersaw can easily cut down trees from Sprout, making it very difficult for Nature's Prophet to teleport away or trap enemies.
* Timbersaw's abilities quickly clear out treants.
* Reactive Armor negates most of the damage of Nature's Prophet's treants, and Timbersaw can often allow himself to be attacked in order to heal himself.

* The percentage-based primary-attribute reduction effect of Whirling Death can be devastating for Pudge due to his high strength gain through Flesh Heap.
* Reactive Armor's health regeneration and common itemization for magic resistance and durability make Timbersaw a poor target for Pudge.
* Timber Chain's high mobility makes Timbersaw difficult to lockdown for Pudge, given he only has one reliable disable.

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

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

* Timbersaw's pure damage will kill Dragon Knight surprisingly fast, especially if he gets caught in a bad position while laning.

* With Timber Chain, Timbersaw can slow, catch up with, or escape from Chen and his creeps.
* Chakram can clear Chen's creeps and slow him.
* Attacks from multiple creeps quickly build Reactive Armor stacks.

* Reactive Armor helps Timbersaw sustain harassment from Stifling Dagger, as well as ganking attempts.
* Phantom Assassin is a hero with moderate HP pool, and usually appears in the front line of battle. Because Blur does nothing against spells, she is vulnerable to Timbersaw's skills.
* Timbersaw can easily escape from Phantom Assassin thanks to his Timber Chain.
Additional:
* Reactive Armor helps Timbersaw sustain harassment from Stifling Dagger.
* Phantom Assassin has a moderate health pool and usually appears in the front line of battle, making her vulnerable to Timbersaw's magic burst.
* Timbersaw can easily escape from Phantom Assassin thanks to his Timber Chain.

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

* Timbersaw's innate tankiness is very hard to deal with as Naga Siren. Timbersaw's high Pure Damage and spammable AoE nukes can also destroy Naga Siren's illusions very fast.

* Razor deals mostly physical damage towards the later game, and Timbersaw is also very mobile, making him a difficult kill to earn.
* Timbersaw rarely resorts to attacks, thus does not suffer when his damage is stolen with Static Link.

* 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.

* 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.

* Reactive Armor is very effective against Beastmaster's summons during laning stage and entire game.
* Timbersaw can quickly clear Beastmaster's summons with his nukes.

* 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.

* Not only are all of Timbersaw's active abilities capable of cutting down trees, but Whirling Death and Timber Chain also require it to be effective, counteracting both Treant Protector's Nature's Guise and Eyes in the Forest abilities.
Additional:
* Timbersaw can use his plethora of tree cutting abilities to level entire sections of the forest, making hiding in the trees more difficult for Treant Protector and his team.
* Timbersaw can easily cut down Treant Protector's Eyes In The Forest once his team has detection. He may even do it unknowingly due to the sheer destructive and chaotic nature of his abilities.

* 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.

* Spiderlings deal almost no damage against Reactive armor. They also die quickly from Timbersaw's AoE abilities.
* Broodmother has no mobility ability except the movement speed buff from Spin Web, allowing Timbersaw to easily escape her Incapacitating Bite with Timber Chain.
* Timbersaw's tree-cutting abilities makes it difficult for Broodmother to hide, especially near the edges of the map.
Additional:
* Reactive Armor prevents Broodmother's spiderlings from being able to effectively harass Timbersaw in the lane.
* Timber Chain's high mobility makes Incapacitating Bite's slow irrelevant.
* Timbersaw's abilities can destroy any trees that Broodmother attempts to hide in and his AoE abilities can quickly clear her Spiderlings.

* 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.

* Timbersaw: Lone Druid will have a hard time dealing with Timbersaw due to his tankiness and high Armor from Reactive Armor

* Reactive Armor makes Timbersaw very effective against heroes that control a lot of units, such as Broodmother, Lycan and Undying.

Additional:
* All of Timbersaw's spells deal AoE damage, killing Lycan's summons very quickly.
* Reactive Armor will gain stacks quickly because of Lycan's summons.

* Heroes who are not easily crippled by Fate's Edict or Fortune's End, such as Timbersaw, or those who can dispel them, such as Phantom Lancer, can kill Oracle unhindered.

* 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.

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

* The burst damage from Timbersaw's abilities is more than enough to deal with Enchantress and her creeps.
* Timbersaw doesn't rely on his physical attacks, which makes Untouchable useless against him.
* Timber Chain can close the gap between them and minimize damage from Impetus.
* Be aware, however, that Timber Chain could work against him if used to escape.
* However, Impetus can ignore Reactive Armor if Enchantress is not a primary target for Timbersaw or if he is disabled.

* Timbersaw can take down Terrorblade's illusions with his area damage burst.
* Reactive Armor plus another armor item reduce much of Terrorblade's damage.
Additional:
* Timbersaw's spell combos all deal magical and pure damage, completely ignoring Terrorblade's high base armor and clearing his illusions very quickly due to the AoE damage.
* Reactive Armor negates most of Terrorblade's damage against Timbersaw, and its high health regeneration and armor bonuses can help Timbersaw survive after being Sundered.

* Timbersaw can use Chakram as a scouting tool to find Slark if he tries to Pounce into the trees.
* None of Timbersaw's abilities require a target to be cast, allowing him to hit Slark inside Shadow Dance.
* Reactive Armor can be effective protection against a Slark who attacks quickly, since the strong armor and health regen cannot be stolen by Essence Shift.
* Timber Chain makes Timbersaw very mobile, meaning he is among the very few heroes who can actually give chase to a fleeing Slark.

* Because multiple Meepos tend to clump up, they present an easy target for Timbersaw's many area abilities.

* Reactive Armor helps Timbersaw to endure the damage from Chaos Bolt and Reality Rift combo.
* Timbersaw's large amount of pure damage AoE nukes clears Chaos Knight's illusions quickly, drastically reducing his damage.
Additional:
* Strong area damage, particularly from Whirling Death and Chakram, lets Timbersaw clear out illusions quickly.
* Whirling Death directly reduces Strength from both Chaos Knight and his Phantasm illusions, reducing both the damage output and raw health that the hero relies on.
* Reactive Armor quickly builds stacks against Phantasm illusions, making Timbersaw hard to kill.
* Timber Chain allows Timbersaw to escape while surrounded.

* Reactive Armor will quickly stack up from Familiar attacks, making Timbersaw hard to kill.
* Visage's low mobility makes it easy for Timbersaw to line up his abilities.

* Timbersaw is often too mobile and durable for Gyrocopter to bring down with his area attacks.

* Timbersaw can easily cut down the tree that Monkey King is standing on, stunning him for a lengthy period.
* Timbersaw can use Timber Chain to easily escape Wukong's Command and Primal Spring's slow.
Additional:
* Timbersaw's low cooldown and low mana cost abilities destroys the trees that Monkey King depends on.
* Timber Chain allows Timbersaw to escape Wukong's Command.

* All Timbersaw's abilities are AOE pure damage and can easily deal with Phantom Lancer's illusions
* Reactive Armor highly negates Phantom Lancer's physical damage, making him having a hard time killing Timbersaw.
Additional:
* Phantom Lancer's lack of burst damage and constant attacks will increase Reactive Armor to max level immediately. Coupled with Timber Chain making escaping from crowds easy, it is almost impossible for Timbersaw to be killed by Phantom Lancer.
* Whirling Death and Chakram can instantly destroy large groups of illusions, negating Phantom Lancer's advantage.

* Heroes that can close the gap can easily chase her down, such as Timbersaw with Timber Chain and Anti-Mage with Blink.

* Timber Chain can kite Troll Warlord extremely effectively.
* Whirling Death and Chakram deals lots of damage to Troll Warlord.
* Reactive Armor makes Timbersaw extremely resilient to Troll's attack damage and extreme attack speed, especially during Battle Trance.