Altar of Dementia

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

Greater Good

Sacrifice a creature: Draw cards equal to the sacrificed creature's power, then discard three cards.

Korozda Guildmage

{1}{B}{G}: Target creature gets +1/+1 and gains intimidate until end of turn. (It can't be blocked except by artifact creatures and/or creatures that share a color with it.)
{2}{B}{G}, Sacrifice a nontoken creature: Create X 1/1 green Saproling creature tokens, where X is the sacrificed creature's toughness.

Infested Thrinax

Flash
When Infested Thrinax enters, until end of turn, whenever a nontoken creature you control dies, create a number of 1/1 green Saproling creature tokens equal to that creature's power.

Hogaak, Arisen Necropolis

You can't spend mana to cast this spell.
Convoke, delve (Each creature you tap while casting this spell pays for {1} or one mana of that creature's color. Each card you exile from your graveyard pays for {1}.)
You may cast Hogaak, Arisen Necropolis from your graveyard.
Trample