Plains

Cast Down

Mortify

Dirty Rat

When this creature enters, target opponent discards a card.

Rat Colony

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

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Forsaken Sanctuary

Forsaken Sanctuary enters tapped.
{T}: Add {W} or {B}.

Ratcatcher

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
At the beginning of your upkeep, you may search your library for a Rat card, reveal it, put it into your hand, then shuffle.

Swamp

Macabre Waltz

Return up to two target creature cards from your graveyard to your hand, then discard a card.

Ruin Rat

Deathtouch
When Ruin Rat dies, exile target card from an opponent's graveyard.

Recover

Return target creature card from your graveyard to your hand.
Draw a card.

Orzhov Guildgate

Orzhov Guildgate enters tapped.
{T}: Add {W} or {B}.

Burglar Rat

When Burglar Rat enters, each opponent discards a card.