Souldrinker

Pay 3 life: Put a +1/+1 counter on this creature.

Mischievous Poltergeist

Flying
Pay 1 life: Regenerate this creature.

Phyrexian Colossus

This creature doesn't untap during your untap step.
Pay 8 life: Untap this creature.
This creature can't be blocked except by three or more creatures.

Deepwood Ghoul

Soul Conduit

{6}, {T}: Two target players exchange life totals.

Shadowcloak Vampire

Pay 2 life: This creature gains flying until end of turn. (It can't be blocked except by creatures with flying or reach.)

Mountain

Carrion Howler

Pay 1 life: This creature gets +2/-1 until end of turn.

Hot Soup

Equipped creature can't be blocked.
Whenever equipped creature is dealt damage, destroy it.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Greven, Predator Captain

Menace
Greven 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.

Swamp

Soul Channeling

Enchant creature
Pay 2 life: Regenerate enchanted creature.

Kuro, Pitlord

At the beginning of your upkeep, sacrifice Kuro unless you pay {B}{B}{B}{B}.
Pay 1 life: Target creature gets -1/-1 until end of turn.

Marrow Bats

Flying
Pay 4 life: Regenerate this creature.

Magus of the Mirror

{T}, Sacrifice this creature: Exchange life totals with target opponent. Activate only during your upkeep.

Wall of Blood

Defender (This creature can't attack.)
Pay 1 life: This creature gets +1/+1 until end of turn.