For the Glory of the Empire!
Little is known of the history of the man/thing known as Grimskull. What is known is that he/it wears black robes and a skull mask at all times, that he/it raised Damien nearly since birth, and that he/it is a powerful member of the faith of Elri’Kah. Grimskull leads one of the most powerful undead mercenary forces in the known world, and has long been at-large.
Grimskull assassinated Duke Duren Kanhilas just before the Battle of Millasilla and imprisoned the Duke’s soul within a dagger. After the battle, Grimskull used the soul of the Duke as leverage to lure Damien Morieu (Grimskull) into a one-on-one meeting/trap.
Grimskull’s reign of terror came to an end at the meeting he orchestrated when Damien Morieu (Grimskull) refused to be taken to Siride and struck his father down in a duel within the ruins of P’Ganthua in the Bloodcrystal Mountains.