Klauth, Unrivaled Ancient 050/062 (The List Reprints)

Flying, haste Whenever Klauth attacks, add X mana in any combination of colors, where X is the total power of attacking creatures. Spend this mana only to cast spells. Until end of turn, you don't lose this mana as steps and phases end.

NM - $23.10
LP - $18.50
MP - $13.90
HP - $9.30
DMG - $4.70