Metanex, King of Ruin

Indestructible
At the beginning of each upkeep, exile the top card of each player's library. You may cast cards exiled this way and spend mana as though it were mana of any color to cast them.
{2}{b}, Sacrifice another artifact or creature: Target opponent loses 3 life, and you gain 3 life. If you sacrificed a creature, Metanex gains Hexproof until end of turn.