Death Tyrant ruler of Gar Mora
An enormous floating skull with a glowing red eye, and ten hovering red lights swirling around it.
When searching for one of his targets in the dwarf-ruin of Gar Mora, Zanzibar ran afoul of this mighty creature. It chased him to the gateway of the buried realm, but did not follow. Nor did it send its dwarven zombies or beholder zombies after him.