Acererak the Archlich
Acererak is a powerful lich known and feared throughout the multiverse. Much of his past is forgotten, but ancient texts assert that he comes from a world called Oerth.
Acererak travels the planes in search of artifacts. When he finds something useful or interesting, he locks it away. Although he’s powerful enough to pursue godhood as other liches have done (Vecna being a prime example), Acererak has no interest in being a god or being worshiped. He prefers to create evil gods and unleash them on mortals and immortals who oppose him.
Although he has lived on many worlds and crafted countless demiplanes, Acererak spends most of his time building tombs. He fills each one with treasure to attract powerful adventurers. He then kills them off in terrible fashion, using deadly traps and monsters while baiting and ridiculing them. The terror he evokes scars their souls, which he traps in his phylactery, the location of which is one of the multiverse’s greatest secrets.
Not too long ago by human standards, Acererak found an atropal adrift at the edge of the Negative Plane and built the Soulmonger to nourish it to godhood. The lich chose one of his tombs—specifically the Tomb of the Nine Gods on Toril—to serve as the atropal’s nursery.