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.

Chittering Rats

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

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Geth's Verdict

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

Barren Moor

Barren Moor enters tapped.
{T}: Add {B}.
Cycling {B} ({B}, Discard this card: Draw a card.)

Dimir Guildmage

({U/B} can be paid with either {U} or {B}.)
{3}{U}: Target player draws a card. Activate only as a sorcery.
{3}{B}: Target player discards a card. Activate only as a sorcery.

Gurmag Angler

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)

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.)

Victim of Night

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

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters, you become the monarch.

Disfigure

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

Swamp

Sign in Blood

Target player draws two cards and loses 2 life.

Whisper Agent

Flash
When Whisper Agent enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)