Alchemist is a melee strength hero that is traditionally played as a safe lane farming hard carry, although since late 2013 his popularity as a support hero (quick support guide here) has increased greatly and he is a viable pick for either role.
‘Carry Alch’ Skills
If you get safe lane freefarm you can risk maxing Greevil’s Greed first – it’s greedy though and leaves you vulnerable to early pressure.
Get a point in Unstable Concoction at level 2 and max it second if you went for the greedy build (otherwise max it first).
Get Acid Spray last if you went for the greedy build (otherwise max it second). Make sure to cast Acid Spray before throwing out your stun for the minus armour – the stun deals physical damage so will be much more potent.
Always get Chemical Rage (levels 6, 11 and 16). Avoid fights when it’s not off cooldown, but don’t be afraid to use it to regen your health when farming.
‘Carry Alch’ Items
Starting Items: A set of Tangos, a Healing Salve, a Quelling Blade, and 3x Iron Branches.
Core (if freefarm): Hand of Midas, Boots of Speed, Magic Wand. Next build Phase Boots or Power Treads.
Core (if fighting early): Magic Wand, Power Treads or Phase Boots, and Shadow Blade.
Core (if vs illusions): Magic Wand, Boots of Speed, Battle Fury. Next build Phase Boots or Power Treads.
Luxury Items: Assault Cuirass, Black King Bar, Abyssal Blade, Mjollnir, Monkey King Bar, Heart of Tarrasque, Heaven’s Halberd, Boots of Travel