A Titan is a colossal walking war machine, among the largest and most devastating engines of destruction the Imperium can field. Towering over the battlefield like a striding fortress, a Titan is armed with weapons powerful enough to level city blocks, annihilate whole formations, and duel with other war engines of its own monstrous scale. So great is its might that a single Titan can decide the fate of an entire battle, and the mightiest classes stand as tall as buildings, their footfalls shaking the earth.
Titans are maintained and crewed by the Collegia Titanica, a martial order bound to the Adeptus Mechanicus, and are regarded as sacred god-machines as much as weapons of war. Each is protected by powerful void shields that absorb incoming fire, and armed with an array of enormous guns, including macro-cannons, that few defences can withstand. To bring one down often requires the concentrated fury of an entire army, or another Titan.
These god-machines range in size from the smaller scout classes to the truly gargantuan battle Titans that anchor an army's might. Their machine spirits are ancient and powerful, and their crews serve as devoted acolytes to the towering war-god they command. When a Titan strides to war, it is as if a wrathful deity has descended upon the battlefield, and few sights in the galaxy inspire such awe and terror.