Alchemist is a melee strength hero that is traditionally played as a safe lane farming hard carry (quick carry guide here), although since late 2013 his popularity as a support hero has increased greatly and he is a viable pick for either role.
‘Support Alch’ Skills
Put your first point in Unstable Concoction and max it first.
Max Acid Spray second of all. 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.
Get Greevil’s Greed last – you’re a support, you need levels in your actives!
Always get Chemical Rage (levels 6, 11 and 16). Use it to regen your health when low and off cooldown, and use it during engagements to make yourself a tanky support.
‘Support Alch’ Items
Starting Items: Courier, Observer Wards, Tangos, Healing Salve, Clarity.
Core Early: Observer Wards, Flying Courier, Boots of Speed, Magic Wand, Medallion.
Core Mid: Observer Wards, Power Treads, Blink Dagger or Force Staff.
Luxury Options: Observer Wards, Mekanism, Drums of Endurance, Pipe of Insight, Vladmir’s Offering, Ghost Scepter, Black King Bar, Heaven’s Halberd, Necronomicon.
Situational: Sentry Wards, Dust of Appearance, Gem of True Sight, Smoke of Deceit.