Mk'ell
From Warhammer 40k - Lexicanum
Mk'ell was an extremely powerful Yuranthos Psyker. He could not control his power, which tore him apart and immolated his entire planet and its population in a psychic firestorm. Unwilling to waste the power of such a talented student, Tzeentch bound the essence of Mk'ell and his dying race into the gem known as the Last Memory of the Yuranthos.[1]
Sources
- 1: Black Legion - A Codex: Chaos Space Marines Supplement (6th Edition) (e-book), pg. 118