Phyrexian Devourer

When Phyrexian Devourer's power is 7 or greater, sacrifice it.
Exile the top card of your library: Put X +1/+1 counters on Phyrexian Devourer, where X is the exiled card's mana value.

Tinker

As an additional cost to cast this spell, sacrifice an artifact.
Search your library for an artifact card, put that card onto the battlefield, then shuffle.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.