Kael'thas, Lord of Felborne

Flying, Menace
Whenever you sacrifice a permanent, you may add one mana of any color. This mana doesn’t empty at end of turn.
If a spell you control with mana value 5 or greater would be countered, you may sacrifice another nonland permanent instead. If you do, that spell resolves.

“Power. Real power. It is not given. It is claimed—with fire and blood.”