Teruleg, Processor of Planes

Ingest X where X is the amount of combat
damage dealt to a player, Devoid
At the beginning of your upkeep, you may put
a card an opponent owns from exile into their graveyard, you get colorless mana equal to that
cards CMC.
Colorless mana doesnt empty out of
your mana pool.
Teruleg gets +1/+1 for each colorless mana in
your mana pool