* The constant dispel from Demonic Purge will make any attempt to save the victim or himself by Surge become futile. For what it's worth, Demonic Purge will also dispel Ion Shell.

* 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.

* Flame Guard makes Dark Seer not deal any damage with his skills to Ember Spirit.

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

* X Marks the Spot prevents Dark Seer or his allies from escaping with Surge.

* 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.

* Strong laners are usually at a disadvantage because of how well Sven can jungle. Heroes such as Dark Seer. Underlord and Legion Commander may find that later Sven takes care of them very quickly after some jungle farming.

* Heroes who struggle to fight back against Sven at any point in the game are at a severe disadvantage: Alchemist, Anti-Mage, Crystal Maiden.

* Fortune's End dispels Ion Shell and Surge, making any gank attempt on Dark Seer in the laning phase likely to succeed.
* Fate's Edict prevents all magical damage that comes from Dark Seer's abilities.
* Fortune's End dispels Ion Shell on creeps, which Dark Seer relies on to farm and zone.
Additional:
* Fortune's End can dispel Ion Shell, a skill that helps Dark Seer immensely in the laning phase, as well as Surge, a move-speed buff, effectively allowing Oracle to control Dark Seer, especially in the laning phase.

* Ice Blast nullifies the health regeneration granted by Chemical Rage, which Alchemist greatly relies on to stay alive in battle.
* Alchemist tends to build Armlet of Mordiggian which can be deadly during Ice Blast.
Additional:
* Ice Blast cancels out Chemical Rage's rapid health regeneration. It can also take advantage of Alchemist's Armlet of Mordiggian toggling, as it will make HP drain insanely fast, essentially killing the bearer in no time.

* Axe can force Alchemist to attack him with Berserker's Call. High attack speed from Chemical Rage will cause Counter Helix to proc multiple times.
* This can get worse if axe has Blade Mail, which then returns all damage to Alchemist himself.
* Axe's abilities can pierce through Black King Bar, which is a common item for Alchemist.
* Berserker's Call grants Axe a huge bonus armor, which greatly counters Alchemist's physical damage for the most part.

* A Sniper who is somewhat competent at positioning is hardly going to be affected by any of Dark Seer's spells thanks to Take Aim.
* However, an illusion of Sniper made with Wall of Replica is extremely powerful, and hard to deal with.

* Dark Seer's strength lies in his high-mana cost skills. So Mana Break can be a great nuisance for him, since it can reduce his mana and prevent him from casting his spells.
* Mana Void can deal a lot of damage if Dark Seer spent a lot of mana on his abilities.

* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as Disruptor's Kinetic Field or Slark's Pounce.

* 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.

* 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.

* 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.

* 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.

* Spell Steal will easily steal all abilities from Dark Seer.
Additional:
* Spell Steal can perfect from Rubick's steal all abilities from Dark Seer. Rubick's always purchase Aghanim's Scepter can two stolens abilities from Dark Seer's and waiting for seconds for second stolen abilities (example: combinated Vacuum and Wall of Replica) and many different combination.
* A good positoning from Rubick's Spell Steal waiting steal abilities from Dark Seer Wall of Replica and illusion from Wall of Replica Dark Seer's can fighting with effect from outcome steal Wall of Replica from Rubick's.
* Combinated Rubick's steal Surge and Blink Dagger is very important catch from Dark Seer's and enemies.
* Rubick's Telekinesis can lifted up Dark Seer or enemy heroes and throw to Wall of Replica from Rubick's steal.

* Alchemist likes to farm fast and be ahead, unfortunately Lone Druid likes to do the same by taking towers.
* Acid Spray will never prove a threat to Lone Druid or his Spirit Bear.
* Chemical Rage may not prove so useful once Lone Druid procs entangled keeping him in place.
* Monkey King Bar is a very good choice on Lone Druid's Spirit Bear and it directly counters any potential Radiance from Alchemist.
* Assault Cuirass is another very good Spirit Bear item that further makes Alchemist vulnerable to physical damage, which is all Lone Druid does.
* Alchemist is not the kind of hero who wants to go on single target summon units, by the time he has killed the Spirit Bear his teammates might had already been slayed by his teammates. Not to mention Lone Druid can just resummon it, even if he is successful.

* In general, heroes who are melee with no way to fight back can be very easily poked by Monkey King to gain his Jingu Mastery stacks: Dark Seer, Riki, Rubick.

* Alchemist has very bad armor and does not build armor items for the large majority of his build, so Jingu Mastery and Wukong's Command can be very deadly.
* Desolator, Sange and Yasha or Diffusal Blade can all be purchased to increase your damage against Alchemist or just to keep your movement speed high enough to match him while Chemical Rage is active.
* Monkey King is an agility hero and scales with armor, so Acid Spray loses it's effectiveness later in the game.

* 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.

* Heroes who rely on physical damage output to be effective will fare badly against Muerta's Pierce the Veil: Phantom Assassin, Terrorblade, Drow Ranger, Lifestealer, Anti-Mage, Alchemist, Lycan, Clinkz, Sniper.

* Dark Seer's only disable is Vacuum. Though he starts off with high armor and health, he'll eventually have a hard time dealing with high mobility heroes such as Weaver or Queen of Pain.

* 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.

* Dark Seer's only disable is Vacuum. Though he starts off with high armor and health, he'll eventually have a hard time dealing with high mobility heroes such as Weaver or Queen of Pain.

* 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.

* Heroes with fast movement abilities will suffer huge damage when afflicted by Rupture: Spirit Breaker, Earth Spirit, Dark Seer.

Additional:
* Rupture can deal a lot of damage to either a surged Dark Seer or his allies and prevent the target from getting into position.

* Abilities that deal low damage with high amounts of instances are irrelevant against Pudge during Flesh Heap's active: Gyrocopter's Rocket Barrage and Dark Seer's Ion Shell are just a couple examples.

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

* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as Disruptor's Kinetic Field or Slark's Pounce.

* Heroes who are melee but cannot fight back against Eclipse will really struggle with Luna: Monkey King, Alchemist, Timbersaw.

* 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.

* 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.
* Since Lifestealer build Aghanim's Scepter upgrades Infest similliar Heaven's Halberd can applies an undispellable disarm so Alchemist cannot attack during Chemical Rage, forcing him to activate Black King Bar beforehand.

* 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.

* Sprout is good for trapping melee carries with no escape abilities: Sven, Alchemist, Lifestealer etc.

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

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

* Heroes without blink mechanisms or spell immunity will have a hard time positioning against Pit of Malice: Sven, Tiny, Wraith King, Dragon Knight, Meepo, Doom, Bounty Hunter, Dark Seer, Undying, Alchemist, Legion Commander.

* 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 thanks to his Atrophy Aura, and will also be unable to ambush Underlord and his team if Underlord chooses to use Fiend's Gate 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.

* Doom can disable Chemical Rage's increased healing, rendering Alchemist helpless against Doom.
* Attacks from Infernal Blade can deal serious damage to Alchemist as it deals damage based on the hero's maximum health.

* Heroes who rely on burst physical damage are affected by Lucky Shot's disarm: Terrorblade, Sven, Clinkz, Windranger, Alchemist, Dragon Knight, Legion Commander