The Darklight

When The Darklight is put into the graveyard or
exile from anywhere, you may put it into your
library fourth from the top.
At the beginning of each opponent's upkeep, exile
the top card of their library. You may cast spells
exiled this way as long as they remain exiled,
spending mana as though it were any color to cast
them. If a nonland card is exiled this way, you gain
life equal to its mana value. If a land is exiled this
way, draw a card.