Dreadwurm

Landfall — Whenever a land you control enters, Dreadwurm gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Oubliette

When Oubliette enters, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)

Night's Whisper

Cemetery Gate

Defender (This creature can't attack.)
Protection from black

Swamp

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.)

Duress

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

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Dimir Guildgate

This land enters tapped.
{T}: Add {U} or {B}.

Dark Ritual

Chainer's Edict

Target player sacrifices a creature of their choice.
Flashback {5}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)