Jesse's World 5th Edition
General: Kostchtchie is the demon lord of evil giants, though typically frost giants and evil bands of humanoids are his most numerous followers. Kostchtchie is a giant, bandy-legged, misshapen humanoid with yellowish skin. He wields a giant warhammer in battle and is prone to murderous rages where ally and enemy alike are targets of his wrath. Kostchtchie’s symbol is an ice-caked warhammer graven with foul runes the color of blood.
History: Legends tell that before Kostchtchie was a demon lord, he was actually a particularly evil and bloodthirsty human who sold his soul to the Witch Queen Baba Yaga for immortality. When his enemies finally cornered and subdued Kostchtchie, they found him impossible to kill so they instead banished him to the Abyss where, after centuries of hate-filled violence, he managed to subdue and bend an entire layer of the plane to his will. Now he rules supreme from his palace of blood and ice within the heart of the 23rd layer of the Abyss, the Iron Wastes.