Crypt Rats

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

Mind Warp

Look at target player's hand and choose X cards from it. That player discards those cards.

Blanket of Night

Each land is a Swamp in addition to its other land types.

Elkin Lair

At the beginning of each player's upkeep, that player exiles a card at random from their hand. The player may play that card this turn. At the beginning of the next end step, if the player hasn't played the card, they put it into their graveyard.

Stone Rain

Volcanic Geyser

Volcanic Geyser deals X damage to any target.

Tormenting Voice

As an additional cost to cast this spell, discard a card.
Draw two cards.

Militant Angel

Flying, lifelink
When Militant Angel enters, create a number of 2/2 white Knight creature tokens with vigilance equal to the number of opponents you attacked this turn.

Anvil of Bogardan

Players have no maximum hand size.
At the beginning of each player's draw step, that player draws an additional card, then discards a card.

Terror

Destroy target nonartifact, nonblack creature. It can't be regenerated.

Relentless Rats

Relentless Rats gets +1/+1 for each other creature on the battlefield named Relentless Rats.
A deck can have any number of cards named Relentless Rats.

Staunch Defenders

When Staunch Defenders enters, you gain 4 life.

Rat Colony

Rat Colony gets +1/+0 for each other Rat you control.
A deck can have any number of cards named Rat Colony.