Alchemist really needs some love, as it is right now he is quite underwhelming and rarely picked due to being squishy in nature owing to bad stat gains unless he itemizes for it which will then lead him to being able to do little to no damage.
And even when he does manage to be so far ahead of the enemy team, once they get items Alchemist ends up being barely able to fight any other carry.
So I propose some suggestions on how to bring him back in the game. The proposal I bring revolves more around giving Alchemist or a potential ally an uncapped potential to grow.
-Has a secondary component
-"Lingering Acid" Armor Reduction from being hit by the initial cast of Acid Spray now have a weaker albeit permanent effect that stacks infinitely. (Preferably around .2/2.5/3/3.5 armor per cast)
-Stays the same but has a secondary component
-"Toxic Spill" Attacks have a chance to release a conoction that does not hit in an aoe does only a mini stun and does only a portion of the damage of the skill (30/45/60/75 damage)
-Stays the same but now has a secondary component
-"Unending Greed" Killing a hero grants permanent increase in the bounty given from creeps and heroes which stack infinitely (killing creeps also grant a increase in permanent bounty of 1 gold but only stack until a maximum limit of 50)
There is something about infinite scaling that makes people want to play said heroes (Enigma, Pudge, and Clinkz for one are almost in every game due to infinite scaling)
-"Chemical Waste" The active otherwise remains the same but gives a portion of the active buff to Alchemist as a passive
-Aghanims upgrades no longer have a limit and can stack infinitely on alchemist and his allies
-Aghanim upgrades on Alchemist increase the portion given as passive