Swamp

Sanguine Bond

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

Anguished Unmaking

Exile target nonland permanent. You lose 3 life.

Astarion's Thirst

Exile target creature. Put X +1/+1 counters on a commander creature you control, where X is the power of the creature exiled this way.

Plains

Blood Tribute

Kicker—Tap an untapped Vampire you control. (You may tap a Vampire you control in addition to any other costs as you cast this spell.)
Target opponent loses half their life, rounded up. If this spell was kicked, you gain life equal to the life lost this way.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Scytheclaw

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1.
Whenever equipped creature deals combat damage to a player, that player loses half their life, rounded up.
Equip {3}

Peer into the Abyss

Target player draws cards equal to half the number of cards in their library and loses half their life. Round up each time.

Astarion, the Decadent

Deathtouch, lifelink
At the beginning of your end step, choose one —
• Feed — Target opponent loses life equal to the amount of life they lost this turn.
• Friends — You gain life equal to the amount of life you gained this turn.

Exquisite Blood

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

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.

Raving Dead

Deathtouch
At the beginning of combat on your turn, choose an opponent at random. Raving Dead attacks that player this combat if able.
Whenever Raving Dead deals combat damage to a player, that player loses half their life, rounded down.

Fraying Omnipotence

Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control of their choice. Round up each time.

Quietus Spike

Equipped creature has deathtouch.
Whenever equipped creature deals combat damage to a player, that player loses half their life, rounded up.
Equip {3}