Hyborem is a Hero unit for the Infernal civilization that comes into existence when a civilization researches Infernal Pact. Hyborem starts with the Immortal promotion, but does not regain it upon his death--to permanently rid the world of Hyborem, he must be killed twice: once to remove the Immortal promotion (at which point he will respawn in the Infernal capitol), and a second time to truly kill him. A bonus of killing Hyborem is that the Infernals will lose all leader traits except Fallow upon his death.