Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Phyrexian Rager

When Phyrexian Rager enters, you draw a card and you lose 1 life.

Chittering Rats

When Chittering Rats enters, target opponent puts a card from their hand on top of their library.

Dross Golem

Affinity for Swamps (This spell costs {1} less to cast for each Swamp you control.)
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

Duress

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

Doom Blade

Disfigure

Target creature gets -2/-2 until end of turn.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Dauthi Slayer

Shadow (This creature can block or be blocked by only creatures with shadow.)
Dauthi Slayer attacks each combat if able.

Choking Sands

Destroy target non-Swamp land. If that land was nonbasic, Choking Sands deals 2 damage to the land's controller.

Swamp

Geth's Verdict

Target player sacrifices a creature of their choice and loses 1 life.

Okiba-Gang Shinobi

Ninjutsu {3}{B} ({3}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Okiba-Gang Shinobi deals combat damage to a player, that player discards two cards.

Victim of Night

Destroy target non-Vampire, non-Werewolf, non-Zombie creature.

Blind Zealot

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever Blind Zealot deals combat damage to a player, you may sacrifice it. If you do, destroy target creature that player controls.

Bottle Gnomes

Sacrifice Bottle Gnomes: You gain 3 life.

Wrench Mind

Target player discards two cards unless they discard an artifact card.

Relic of Progenitus

{T}: Target player exiles a card from their graveyard.
{1}, Exile Relic of Progenitus: Exile all graveyards. Draw a card.

Sign in Blood

Target player draws two cards and loses 2 life.

Grim Harvest

Return target creature card from your graveyard to your hand.
Recover {2}{B} (When a creature is put into your graveyard from the battlefield, you may pay {2}{B}. If you do, return this card from your graveyard to your hand. Otherwise, exile this card.)