Altar of Bone [Ice Age]Set: Ice Age Type: Sorcery Rarity: Rare Cost: {G}{W} As an additional cost to cast this spell, sacrifice a creature. Search your library for a creature card, reveal it, put it into your hand, then shuffle.

Set: Avacyn Restored Type: Enchantment Rarity: Rare Cost: {4}{B} Whenever an opponent loses life

You may repeat this process any number of times

If you control an Urza's Mine and an Urza's Power-Plant

yet subtle utility

Sacrifice Arid Mesa: Search your library for a Mountain or Plains card

Set: Magic 2011 Promos Type: Creature — Ooze Rarity: Rare Cost: {4}{G} When Mitotic Slime dies

They have "When this creature dies

and cannot be truly contained

sacrifice Koskun Falls unless you tap an untapped creature you control

When you control no lands

Set: Beta Edition Type: Land — Swamp Forest Rarity: Rare ({T}: Add {B} or {G}

will fight them for you