Phyrexian Devourer + Fling

Cast Phyrexian Devourer.

Activate Phyrexian Devourer's ability, exiling cards from the top of your library one at a time to add +1/+1 counters equal to each card's mana value.

When the sacrifice trigger occurs (power >= 7), respond to it by stacking additional activations to grow Devourer's power to a lethal amount.

Cast Fling, sacrificing Phyrexian Devourer to deal lethal damage to your opponent.