Swamp

Ossuary Rats

When Ossuary Rats enters, it deals X damage to target creature or planeswalker an opponent controls, where X is the number of creature cards in your graveyard.

Ulcerate

Target creature gets -3/-3 until end of turn. You lose 3 life.

Howl of the Hunt

Flash
Enchant creature
When Howl of the Hunt enters, if enchanted creature is a Wolf or Werewolf, untap that creature.
Enchanted creature gets +2/+2 and has vigilance.

Mild-Mannered Librarian

{3}{G}: Mild-Mannered Librarian becomes a Werewolf. Put two +1/+1 counters on it and you draw a card. Activate only once.

Arlinn, Voice of the Pack

Each creature you control that's a Wolf or a Werewolf enters with an additional +1/+1 counter on it.
−2: Create a 2/2 green Wolf creature token.

Howlgeist

Creatures with power less than Howlgeist's power can't block it.
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Master of the Wild Hunt

At the beginning of your upkeep, create a 2/2 green Wolf creature token.
{T}: Tap all untapped Wolf creatures you control. Each Wolf tapped this way deals damage equal to its power to target creature. That creature deals damage equal to its power divided as its controller chooses among any number of those Wolves.

Ashcoat of the Shadow Swarm

Whenever Ashcoat of the Shadow Swarm attacks or blocks, other Rats you control get +X/+X until end of turn, where X is the number of Rats you control.
At the beginning of your end step, you may mill four cards. If you do, return up to two Rat creature cards from your graveyard to your hand. (To mill a card, put the top card of your library into your graveyard.)

Thriving Moor

Thriving Moor enters tapped. As it enters, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Pestilent Wolf

{2}{G}: Pestilent Wolf gains deathtouch until end of turn.

Chittering Rats

When Chittering Rats enters, target opponent puts a card from their hand on top of their library.

Nezumi Bone-Reader

{B}, Sacrifice a creature: Target player discards a card. Activate only as a sorcery.

Sinuous Vermin

{3}{B}{B}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
As long as Sinuous Vermin is monstrous, it has menace. (It can't be blocked except by two or more creatures.)

Typhoid Rats

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Infiltration Lens

Whenever equipped creature becomes blocked by a creature, you may draw two cards.
Equip {1}

Ogre Slumlord

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.
Rats you control have deathtouch.

Eviscerate

Thriving Grove

Thriving Grove enters tapped. As it enters, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.

Ferocious Pup

When Ferocious Pup enters, create a 2/2 green Wolf creature token.

Bounding Wolf

Crypt Rats

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

Moonlight Hunt

Choose target creature you don't control. Each creature you control that's a Wolf or a Werewolf deals damage equal to its power to that creature.

Prey Upon

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Burglar Rat

When Burglar Rat enters, each opponent discards a card.

Spectral Hunt-Caller

{5}{G}: Creatures you control get +1/+1 and gain trample until end of turn.

Forest

Young Wolf

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)