Mirrorfiend

The Mirrorfiend is a Daemon Engine of Tzeentch from the setting of Black Crusade, created by imprisoning a Lord of Change inside a giant mechanical beetle, which can scurry across the harshest terrain on mechanical legs or soar through the air on wings of light. Native to the city of Tarnor on the Tzeentch-worshipping renegade world of Q'Sal, these terrible engines make use of potent psychic powers to cripple, maim and mutate victims before rending them apart with giant daemonflesh pincers. Their most lethal ability is their Mirror of Souls, a psychic aura that attacks the resolve of those who look at it, its mirror-like surface displaying all their doubts, fears and regrets for them to see in hideous lividity. Worse, this aura is especially powerful against those who worship the God-Emperor of Mankind, as it resolves on feeding on their most subconscious fears and doubts regarding his existence, divinity or very life.

You wish there were official rules for a unit this badass!