Bolas' Studies

When Bolas' Studies enters the battlefield, exile
the top card of your library. Until end of turn,
you may play cards exiled this way.
Whenever you gain life, you cast a creature spell,
or you draw a card, put a study counter on
Bolas' Studies.
Sacrifice this enchantment, remove seven study counters from Bolas' Studies: Target opponent sacrifices a creature, discards three cards, then
loses 5 life. Activate this ability only as a sorcery.