Snow-Covered Swamp

Vito, Thorn of the Dusk Rose

Whenever you gain life, target opponent loses that much life.
{3}{B}{B}: Creatures you control gain lifelink until end of turn.

Underworld Dreams

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

Vampire of the Dire Moon

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Defiant Bloodlord

Flying
Whenever you gain life, target opponent loses that much life.

Bloodthirsty Aerialist

Flying
Whenever you gain life, put a +1/+1 counter on Bloodthirsty Aerialist.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.