Souldrinker

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

Wall of Blood

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

Carrion Howler

Pay 1 life: Carrion Howler gets +2/-1 until end of turn.

Mountain

Phyrexian Colossus

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

Mischievous Poltergeist

Flying
Pay 1 life: Regenerate Mischievous Poltergeist.

Soul Conduit

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

Shadowcloak Vampire

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

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.)

Marrow Bats

Flying
Pay 4 life: Regenerate Marrow Bats.

Kuro, Pitlord

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

Swamp

Deepwood Ghoul

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

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.

Soul Channeling

Enchant creature
Pay 2 life: Regenerate enchanted creature.

Magus of the Mirror

{T}, Sacrifice Magus of the Mirror: Exchange life totals with target opponent. Activate only during your upkeep.