Thud

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

Yargle, Glutton of Urborg

Chandra's Ignition

Target creature you control deals damage equal to its power to each other creature and each opponent.

Greven, Predator Captain

Menace
Greven, Predator Captain gets +X/+0, where X is the amount of life you've lost this turn.
Whenever Greven attacks, you may sacrifice another creature. If you do, you draw cards equal to that creature's power and you lose life equal to that creature's toughness.

Blood-Chin Fanatic

{1}{B}, Sacrifice another Warrior creature: Target player loses X life and you gain X life, where X is the sacrificed creature's power.

Reiterate

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Copy target instant or sorcery spell. You may choose new targets for the copy.

Heart-Piercer Manticore

When Heart-Piercer Manticore enters, you may sacrifice another creature. When you do, Heart-Piercer Manticore deals damage equal to that creature's power to any target.
Embalm {5}{R} ({5}{R}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Manticore with no mana cost. Embalm only as a sorcery.)

Fork

Copy target instant or sorcery spell, except that the copy is red. You may choose new targets for the copy.