Warlock is a ranged intelligence hero who is typically played in public matchmaking as a support hero, but when picked competitively tends to take on a core role (usually mid). Depending on the enemy line-up he is viable in either role.
He is mostly picked for his devastating teamfight ultimate and the ability to ensure that damage done to enemies is transferred to their allies.
Skills
Fatal Bonds is skilled and maxed second.
Shadow Word is skilled and maxed first.
Upheaval is skilled nad maxed last.
Chatoic Offering is always skilled (levels 6, 11 and 16).
Items
Starting Items: Courier and/or Observer Wards, Tangos, Healing Salve, 3x Iron Branches, Clarity.
Early Game: Flying Courier, Observer Wards, Boots of Speed, Magic Wand.
Core Items: Arcane Boots, Mekanism.
Luxury Options: Aghanim's Scepter, Refresher Orb, Necronomicon, Force Staff, Drums of Endurance, Heaven's Halberd, Ghost Scepter, Rod of Atos.
Situational Items: Boots of Travel (late game), Pipe of Insight (if didn't get Mekanism), Vladmir's Offering (utility for team, melee cores).
