Extremely rare, invulnerable, and silent until the very end.
Rezxqu is exclusive to Corruption Level 2 and extremely rare, roughly a 1-in-12,000 chance to spawn. It is invulnerable and follows the player in silence.
After 1 second it delivers the clan's farewell message, "this world is our grave...", and getting within 1.5 blocks kicks the player from the world: twice in a row in unsafe mode ("you are not whitelisted"), once in safe mode.