Witness Protection

Enchant creature
Enchanted creature loses all abilities and is a green and white Citizen creature with base power and toughness 1/1 named Legitimate Businessperson. (It loses all other colors, card types, creature types, and names.)

Infestation Sage

When this creature dies, create a 1/1 black and green Insect creature token with flying.

Gutless Plunderer

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Raid — When this creature enters, if you attacked this turn, look at the top three cards of your library. You may put one of those cards back on top of your library. Put the rest into your graveyard.

Revenge of the Rats

Create a tapped 1/1 black Rat creature token for each creature card in your graveyard.
Flashback {2}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Grappling Kraken

Landfall — Whenever a land you control enters, tap target creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Ravenous Amulet

{1}, {T}, Sacrifice a creature: Draw a card and put a soul counter on this artifact. Activate only as a sorcery.
{4}, {T}, Sacrifice this artifact: Each opponent loses life equal to the number of soul counters on this artifact.

Billowing Shriekmass

Flying
When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)
Threshold — This creature gets +2/+1 as long as there are seven or more cards in your graveyard.

Bigfin Bouncer

When this creature enters, return target creature an opponent controls to its owner's hand.

Crypt Feaster

Menace (This creature can't be blocked except by two or more creatures.)
Threshold — Whenever this creature attacks, if there are seven or more cards in your graveyard, this creature gets +2/+0 until end of turn.

Rune-Sealed Wall

Defender
{T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Vampire Nighthawk

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Swamp

Cephalid Inkmage

When this creature enters, surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Threshold — This creature can't be blocked as long as there are seven or more cards in your graveyard.

Refute

Counter target spell. Draw a card, then discard a card.

Zombify

Return target creature card from your graveyard to the battlefield.

Nine-Lives Familiar

This creature enters with eight revival counters on it if you cast it.
When this creature dies, if it had a revival counter on it, return it to the battlefield with one fewer revival counter on it at the beginning of the next end step.

Stromkirk Bloodthief

At the beginning of your end step, if an opponent lost life this turn, put a +1/+1 counter on target Vampire you control.

Hungry Ghoul

{1}, Sacrifice another creature: Put a +1/+1 counter on this creature.

Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.

Think Twice

Draw a card.
Flashback {2}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)