Ancestral Redemption.
"I may have failed severally in the past...but my past is my prologue."
After a primordial demiurge is manacled into oblivion by rebelling descendants, he yearns for a jailbreak. However, this possiblity seems ineluctable, because his own bloodlines are all teamed up against him.
However, a tiny sliver of hope gleams around. The last descendant and runt of his very own dynasty, Umbra Ashmedai realizes the true reason for which he was blessed to be a cursed 'vessel'.
He transcends known impossibilities and oversteps mortal bounds, spurred by a borrowed quest revenge and painful experiences.
A curse backslash transmutes his dream, and bestows upon Umbra, the irrevocable destiny of being the arch-nemesis of the greatest antagonist demiurge ever existed.