Crypt Rats

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

Have

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.

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.

Ichor Wellspring

When Ichor Wellspring enters or is put into a graveyard from the battlefield, draw a card.

Bojuka Bog

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

Cast Down

Snow-Covered Swamp

Lembas

When Lembas enters, scry 1, then draw a card.
{2}, {T}, Sacrifice Lembas: You gain 3 life.
When Lembas is put into a graveyard from the battlefield, its owner shuffles it into their library.

Duress

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

Moment of Craving

Target creature gets -2/-2 until end of turn. You gain 2 life.

Toxin Analysis

Target creature gains deathtouch and lifelink until end of turn. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Cauldron Familiar

When Cauldron Familiar enters, each opponent loses 1 life and you gain 1 life.
Sacrifice a Food: Return Cauldron Familiar from your graveyard to the battlefield.

Desert

{T}: Add {C}.
{T}: Desert deals 1 damage to target attacking creature. Activate only during the end of combat step.

Defile

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

Retrofitted Transmogrant

{3}{B}: Return Retrofitted Transmogrant from your graveyard to the battlefield tapped with two +1/+1 counters on it.

Eviscerator's Insight

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards.
Flashback {4}{B} (You may cast this card from your graveyard for its flashback cost and any additional costs. Then exile it.)

Consuming Sepulcher

At the beginning of your upkeep, each opponent loses 1 life and you gain 1 life.

Tithing Blade

When Tithing Blade enters, each opponent sacrifices a creature of their choice.
Craft with creature {4}{B} ({4}{B}, Exile this artifact, Exile a creature you control or a creature card from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Tithing Blade // Consuming Sepulcher

Tanglebloom

Nihil Spellbomb

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard.
When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Candy Trail

When Candy Trail enters, scry 2.
{2}, {T}, Sacrifice Candy Trail: You gain 3 life and draw a card.

Extract a Confession

As an additional cost to cast this spell, you may collect evidence 6. (Exile cards with total mana value 6 or greater from your graveyard.)
Each opponent sacrifices a creature of their choice. If evidence was collected, instead each opponent sacrifices a creature with the greatest power among creatures they control.

Troll of Khazad-dûm

Troll of Khazad-dûm can't be blocked except by three or more creatures.
Swampcycling {1} ({1}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

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.)