From Destinypedia, the Destiny wiki
Warlocks are "warrior-scholars," and a class of Guardian. Warlocks utilize powers granted by the Traveler for both attack and defense. Warlocks specialize in ranged melee attacks and casting elemental spells to take out enemies.
Warlocks were the first to tap the power of the Traveler, wielding its light as they ventured beyond the safety of the Wall. They know each discovery offers new possibilities, and they have devoted themselves to understanding the Traveler, its power, and how to better channel that power. A Warlock mind is an arsenal of deadly secrets, balanced between godhood and madness. On the battlefield, those secrets can shatter reality itself. They search the frontier to find a means to defeat the Darkness once and for all.
Warlocks are known for pushing the boundaries of knowledge, even into dangerous territory. At least two warlocks, Toland, the Shattered and Osiris, were exiled for studying the Hive and Vex too closely. There also exists an order of warlocks called the Thanatonauts, who take advantage of Guardians ability to resurrect themselves to receive visions every time they die.
All Guardians have certain abilities, some of which are granted by the Traveler, others which may appear more mundane in nature. All Guardians have a double jump ability and a "grenade-type" ability whose effects vary by class. All these abilities with the exception of the double jump can be upgraded over time and can be used in competitive PvP.
List of appearances