* Corrosive Haze followed by Slithereen Crush takes advantage of Alchemist's main weakness, being physical damage before he has the change to improve his surviability with items.
* Bash of the Deep will deal lots of damage during the laning phase.

* The brutal physical damage of Slithereen Crush and Bash of the Deep can quickly remove Void Spirit's shield and stun him for a while.
* Corrosive Haze provides vision of Void Spirit while he is running away and Guardian Sprint allows Slardar to quickly close the gap

* Ember Spirit has much higher mobility in Fire Remnant than Void Spirit.
* Ember's Flame Guard is effective against Void Spirit's spells, as most of them deal magical damage.
* The root from Searing Chains prevents Void Spirit from using Dissimilate or Astral Step.

* Ember's magic damage build is able to burst down Alchemist due to his low strength gain and Alchemist's normal item pick up.

* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, Lifestealer, or Axe.

* Feast is good against high health strength heroes such as Alchemist.
* Rage allows Lifestealer to not be targetable by Unstable Concoction, possibly making Alchemist stun himself.

* Void Spirit can easily be bursted down by Puck's high magic damage spells in early game.
* Wanning Rift and Dream Coil prevent him from using two of his important mobility abilities: Dissimilate and Astral Step.
Additional:
* Dream Coil prevents the usage of Void Spirit's escape abilities and limits his damage output in fights almost entirely.
* Killing Puck in the late game becomes difficult when they obtain a Eul's Scepter of Divinity, Blink Dagger, and Phase Shift.

* Melee heroes that get kited easily have hard times dealing with Puck without any lockdowns, as Puck is one of the most mobile heroes. Heroes like Sven, Lifestealer, Ursa and Alchemist may have problems to get to Puck without proper initiation items. They also lack reliable lockdowns, as their disables are easily avoidable for Puck, or are just a soft disable.

* Poison Attack makes it hard for Void Spirit to lane against him.
* Corrosive Skin reduces the magical damage from Void Spirit's spells.

* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.

* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, Lifestealer, or Axe.

* Heroes without an escape mechanism: Shadow Fiend, Alchemist

Additional:
* Chemical Rage will rarely save Alchemist against Ursa's Fury Swipes.
* Enrage allows Ursa to both be a threat to Alchemist and avoid his over time damage.

* Queen of Pain can Blink to both escape and initiate onto Void Spirit.
* She is also a very common Orchid Malevolence carrier, which can prevent Void Spirit from contributing much in fights.

* Refraction negates all of Void Spirit's burst damage.
* Meld quickly burns through Resonant Pulse.

* Shadow Dance allows Slark to not be targeted by Unstable Concoction, making Alchemist stun himself and making himself vulnerable to the enemy.
* Dark Pact also allows him to just purge off the stun if timed correctly.
* Essence Shift will steal stats over long durations at a time should Alchemist lack the damage to kill Slark.

* Rupture will fully damage Void Spirit during his ultimate, removing his main escape mechanic during fights and his way to disrupt them heavily.
* Blood Rite will force Void Spirit to use Dissimilate or Astral Step or be silenced. In the latter's case, it can be dangerous when combined with Rupture.

* Spirit Siphon and Exorcism can damage through his Resonant Pulse shields.
* Silence can prevent Void Spirit escape or contributing much in fights.

* Fiend's Grip and Nightmare are very useful to lock down Void Spirit.
* Brain Sap can be difficult for Void Spirit to deal with in the laning stage.

* Alchemist's reliance on fast attack speed to do single-target damage makes him vulnerable to Static Link. It also goes through Black King Bar, which is a standard item on Alchemist.
* Eye of the Storm is great against high health strength heroes as it reduces their survivability to physical damage.
* Razor has early lane push to counter Acid Spray.

* Untouchable greatly reduces Chemical Rage's attack speed advantage.

* Skywrath Mage can easily harass Alchemist in the laning phase with multiple Arcane Bolts. Additionally, if Alchemist is in the process of throwing an Unstable Concoction, and has no way to dispel Ancient Seal, the self stun becomes an easy set up for Mystic Flare.
* Caution, however, as a decently farmed Alchemist with {Item ID:Radiance} and {Item ID:Manta Style} can easily send illusions to harass and force Skywrath Mage out.

* Alchemist is a well-known Radiance carrier among other auras your illusions will benefit from. They also get the extra move speed and reduced base attack time from his Chemical Rage, and it's even better if you can catch him as his own rage is about to expire.
* Disruption will buy enough time for all allies to retreat when Alchemist starts to activate Unstable Concoction.

* Quas-Exort Invoker can win the mid lane easily against Alchemist because Quas regeneration will nullify Acid Spray's damage over time and Exort damage bonus will allow Invoker to out last hit Alchemist.

* Tidebringer will deal lots of damage to Alchemist before he builds physical survivability items.
* Torrent and X Marks the Spot can control Alchemist at all stages of the game before he has Black King Bar.
* Ghostship's rum buff will greatly reduce the Alchemist's damage output in teamfights including his Radiance.

* Reaper's Scythe can kill Alchemist before Chemical Rage has the time to heal him.
* Ghost Shroud can prevent Alchemist from attacking Necrophos, as well as make him immune to Acid Spray and Unstable Concoction damage.
* Heartstopper Aura will do damage as long as Necrophos is alive based on health percentage, which is a problem for a strength hero such as Alchemist.

* One hit with Jinada should be sufficient in removing Void Spirit's shield most of the time.
* Track negates much of Void Spirit's escape abilities by revealing his position and prevents him from rotating effectively.

* Side lanes with disables will greatly reduce the likeliness Void Spirit will be willing to rotate: Sven, Tiny, Wraith King, Ogre Magi.

* Heroes that can purge his slow and disables are very difficult to go on and their team: Abaddon, Oracle.

* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, Lifestealer, or Axe.

* Heroes who can match Void Spirit's mobility (like the aforementioned Ember Spirit or Queen of Pain) or tank his spells (Dragon Knight or Centaur Warrunner) are very problematic for him.

* Clinkz can use Burning Army in teamfights which will cause a problem for Alchemist.

* Heroes who can match Void Spirit's mobility (like the aforementioned Ember Spirit or Queen of Pain) or tank his spells (Dragon Knight or Centaur Warrunner) are very problematic for him.

* Special mention to Legion Commander, as she can lock down Void Spirit for a long amount of time without worrying too much about being killed by him during the Duel.

* Heroes that can purge his slow and disables are very difficult to go on and their team: Abaddon, Oracle.

* Pugna's Decrepify makes sure that either Alchemist is unable to hit anyone while also being slowed and susceptible to magical damage, or can protect an ally from physical attacks. Besides, Pugna can push early on, when Alchemist is not strong enough to repel it, so by the time Alchemist comes online, he might be forced to sit in base.

* Side lanes with disables will greatly reduce the likeliness Void Spirit will be willing to rotate: Sven, Tiny, Wraith King, Ogre Magi.

* Side lanes with disables will greatly reduce the likeliness Void Spirit will be willing to rotate: Sven, Tiny, Wraith King, Ogre Magi.

* In general, attacks of the melee heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him, and will be unable to ambush Underlord and his team if Underlord chooses to use Dark Rift to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, Bounty Hunter, Alchemist, Templar Assassin, Nyx Assassin, Bane.

* Visage can quickly kill heroes with low to medium base armor and no innate escape mechanism. Examples include Alchemist, Crystal Maiden and Zeus.

* Side lanes with disables will greatly reduce the likeliness Void Spirit will be willing to rotate: Sven, Tiny, Wraith King, Ogre Magi.

* Meepo's Earthbind can easily lockdown Void Spirit.
* Meepo and his clones can easily burst Void Spirit's Resonant Pulse.