Warlocks were once arcanists or, in the case of the orcs, shamans — who in pursuit of ever-greater sources of power abandoned their studies of the Nature or Arcane and delved into darker Fel-based magic (Shadow). Warlocks still retain their skills in the manipulation of the chaotic element of Fire, although their focus is on delivering excruciating pain and drawing out the suffering of their victims. No longer do they aim to use the effective application of Arcane energies to efficiently dispose of their targets from a safe distance.
Warlocks are unique among the DPS caster classes because of their ability to convert health into mana. Warlocks have the most powerful assortment of Damage over Time spells when used in conjunction, and also the most variety in debuffs and summonable minions. Just like a Mage, a Warlock’s Crowd control abilities appropriately used can stave off certain doom for the Warlock and their allies, and the Warlock’s sustained Burst damage when suitably specced and geared can rival those of a Mage. However, the Warlock’s Area of Effect spells are not as varied as those of their Mage brethren, although when used appropriately they have powerful applications in group play.
Warlocks are well versed in the "shock and horror" tactics of warfare, and their manipulation of Shadow energies can send their opponents reeling in Fear. At low levels, Warlocks rely primarily on minions and Damage over Time (DoT) spells to deal out damage while fearing their enemies to prevent retribution.
Endgame warlocks either choose to maximize the effects of their DoTs and Curses through the Affliction tree, increase the utility of their summoned minions and stones through the Demonology tree, or lay waste the opposition with Burst damage and Direct damage spells in the Destruction tree. In previous versions of WoW, the 8-debuff and 16-debuff limits prevented Warlocks from maximizing their damage output through Affliction spells, and Warlocks were relegated to chain-casting their Direct damage spells to maintain DPS in PvE raids. This has changed with the new 40-debuff limit, and Affliction DPS is now competitive in a raid environment.
The Warlock can learn to summon magical mounts. Other classes, except Paladins and Druids, must purchase their own mounts with gold or via PvP.
Being a Warlock demands certain things: being able to engage multiple targets simultaneously while keeping tabs on your minion, to make split-second strategic decisions on cast rotations depending on the situation, careful shard management and even more careful aggro management. Being a Warlock also rewards many things: they are PvP powerhouse due to naturally high stamina values, they have the ability to apply debilitating, even humiliating Crowd control abilities and in PvE their damage output in multiple target situations can rival those of other DPS classes who focus fire on a single target.
Their ability to drain and use souls as Soul shards are also appealing to many.
Stamina is one of the key Warlock attributes, especially for Demonology Warlocks. The main reason for this is that Warlocks can convert their health to mana through the spell Life Tap, thus allowing Stamina to mostly fill the role for Intellect as well. Many Warlocks also depend on large health pools as their main source of defense.
As a primary spell caster, the Warlock also has great use for all the standard caster attributes, such as Intellect and Spell damage. Consequently Warlocks have no use for Strength and also little use for Agility. Spirit regenerates health and mana for Warlocks very slowly, giving it no practical use when compared to abilities such as Life Tap and Dark Pact. The value of Spell crit depends on the talent build. With Ruin and the use of direct damage spells, it is very good. But for an Affliction Warlock that mostly uses DoTs, it is worth very little. The Demonology talent, Demonic Knowledge, gives the Warlock bonus spell damage of an amount equal to 5/10/15 percent of their active demon's Stamina + Intellect, which are bolstered by the Warlock's own Stamina and Intellect values.
In a raid scenario, Spell hit rating becomes significantly more valuable, taking precedence over all other stats and it is advisable that you reach the spell hit rating cap (17%, as of 3.0.2). After this point, however, spell hit rating is useless.
The value of item attributes varies greatly for Warlocks depending on their talent choices and their main focus in the game whether it be leveling, raiding or PvP. Below is an example of the Attribute values for a raiding Warlock (in descending order).
In PvP for Warlocks the focus is somewhat different as survivability takes precedence, often forcing Warlocks to greatly sacrifice DPS in order to obtain higher survivability in high end arena regardless of talent choice although all these stats have to be balanced relative to each other for the best results.
Warlocks can wear Cloth armor only, and can initially use Daggers and Unarmed combat in battle. They can also use Wands for ranged combat, and equip off-hands to enhance various skills. They can train at a weapon master for 10 to gain the ability to use One-Handed Swords (Undercity, Silvermoon, Stormwind) and Staves (Orgrimmar, Thunder Bluff, Stormwind, Darnassus). More information regarding Warlock-specific armor can be found at Warlock Sets.