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.

Have

Disentomb

Return target creature card from your graveyard to your hand.

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.

Psychic Whorl

Target opponent discards two cards. Then if you control a Rat, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Cradle to Grave

Destroy target nonblack creature that entered this turn.

Cast Down

Debt to the Kami

Choose one —
• Target opponent exiles a creature they control.
• Target opponent exiles an enchantment they control.

Crypt Rats

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

Witch's Cottage

({T}: Add {B}.)
Witch's Cottage enters tapped unless you control three or more other Swamps.
When Witch's Cottage enters untapped, you may put target creature card from your graveyard on top of your library.

Drown in Sorrow

All creatures get -2/-2 until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Thorn of the Black Rose

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

Raven of Fell Omens

Flying
Whenever you commit a crime, each opponent loses 1 life and you gain 1 life. This ability triggers only once each turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Battle-Rage Blessing

Target creature gains deathtouch and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Arms of Hadar

Creatures target player controls get -2/-2 until end of turn.

Shrivel

All creatures get -1/-1 until end of turn.

Tasigur's Cruelty

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

Sign in Blood

Target player draws two cards and loses 2 life.

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.)

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.)

Unexpected Fangs

Put a +1/+1 counter and a lifelink counter on target creature.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Duress

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

Swamp

Vampire Sovereign

Flying
When Vampire Sovereign enters, target opponent loses 3 life and you gain 3 life.

Seekers' Squire

When Seekers' Squire enters, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Geth's Verdict

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

Nezumi Road Captain

Menace
Vehicles you control have menace. (They can't be blocked except by two or more creatures.)

Okiba Reckoner Raid

(As this Saga enters and after your draw step, add a lore counter.)
I, II — Each opponent loses 1 life and you gain 1 life.
III — Exile this Saga, then return it to the battlefield transformed under your control.