Plaguecrafter

When Plaguecrafter enters the battlefield, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Birthing Pod

({G/P} can be paid with either {G} or 2 life.)
{1}{G/P}, {T}, Sacrifice a creature: Search your library for a creature card with mana value equal to 1 plus the sacrificed creature's mana value, put that card onto the battlefield, then shuffle. Activate only as a sorcery.

Fiend Artisan

Fiend Artisan gets +1/+1 for each creature card in your graveyard.
{X}{B/G}, {T}, Sacrifice another creature: Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle. Activate only as a sorcery.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Savra, Queen of the Golgari

Whenever you sacrifice a black creature, you may pay 2 life. If you do, each other player sacrifices a creature.
Whenever you sacrifice a green creature, you may gain 2 life.