Corpsejack Menace

If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on it instead.

Genghis Frog

Trample
Whenever Genghis Frog or another Mutant you control enters, create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")

Evolution Witness

{1}{G}: Adapt 2. (If this creature has no +1/+1 counters on it, put two +1/+1 counters on it.)
Whenever one or more +1/+1 counters are put on this creature, return target permanent card from your graveyard to your hand.

Ray Fillet, Wave Warrior

Flying
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever a creature you control with a counter on it deals combat damage to a player, draw a card.

High Score

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.
At the beginning of your end step, draw a card if you control a creature with the greatest power among creatures on the battlefield.

Rocksteady, Mutant Marauder

Partner with Bebop, Skull & Crossbones (When this creature enters, target player may put Bebop into their hand from their library, then shuffle.)
Trample
Whenever another nontoken creature you control enters, put a +1/+1 counter on target creature.

Steelbane Hydra

This creature enters with X +1/+1 counters on it.
{2}{G}, Remove a +1/+1 counter from this creature: Destroy target artifact or enchantment.

Dimension X Pizzasaur

When this creature enters, put two +1/+1 counters on target creature. When you do, destroy up to one target creature with mana value less than or equal to the number of counters among permanents you control.
{2}, {T}, Sacrifice this creature: You gain 3 life and each opponent loses 3 life.

Kami of Whispered Hopes

If one or more +1/+1 counters would be put on a permanent you control, that many plus one +1/+1 counters are put on that permanent instead.
{T}: Add X mana of any one color, where X is this creature's power.

Tokka & Rahzar, Unsupervised

First strike
Whenever another nontoken creature you control leaves the battlefield, put a +1/+1 counter on Tokka & Rahzar and create a Treasure token. This ability triggers only once each turn.

Michelangelo, the Heart

Trample
Raid (the Fridge) — At the beginning of your second main phase, if you attacked this turn, put a +1/+1 counter on target creature and create a Food token.
Partner—Character select (You can have two commanders if both have this ability.)

Michelangelo, Weirdness to 11

When Michelangelo enters, create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")
If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Mona Lisa, Science Geek

Reach
{T}: Add X mana of any one color, where X is Mona Lisa's power.

April O'Neil, Human Element

Whenever a player casts an artifact, instant, or sorcery spell, you create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")

Bebop, Skull & Crossbones

Partner with Rocksteady, Mutant Marauder (When this creature enters, target player may put Rocksteady into their hand from their library, then shuffle.)
Deathtouch
Whenever Bebop deals combat damage to a player, you may draw X cards, where X is the number of counters on Bebop. If you do, you lose X life.

Mona Lisa, Ever Adaptable

Whenever a player casts a creature spell, you create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")

Biogenic Ooze

When this creature enters, create a 2/2 green Ooze creature token.
At the beginning of your end step, put a +1/+1 counter on each Ooze you control.
{1}{G}{G}{G}: Create a 2/2 green Ooze creature token.

Anim Pakal, Thousandth Moon

Whenever you attack with one or more non-Gnome creatures, put a +1/+1 counter on Anim Pakal, then create X 1/1 colorless Gnome artifact creature tokens that are tapped and attacking, where X is the number of +1/+1 counters on Anim Pakal.

Venus, Torn Between Worlds

Whenever Venus is dealt damage, put that many +1/+1 counters on her. (She must survive the damage to get the counters.)
Whenever a creature you control with a counter on it deals combat damage to a player, you may pay {U}. If you do, draw a card.

Academy Manufactor

If you would create a Clue, Food, or Treasure token, instead create one of each.

Shredder, Shadow Master

Whenever Shredder attacks a player, for each other opponent, create a token that's a copy of Shredder tapped and attacking that player, except it isn't legendary. Sacrifice those tokens at end of combat.
Whenever Shredder deals combat damage to a player, that player loses half their life, rounded up.

Agent Bishop, Man in Black

At the beginning of combat on your turn, put a +1/+1 counter on each of up to two target creatures.

Krang, the All-Powerful

If a player drawing a card causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Whenever a player draws their second card each turn, put a +1/+1 counter on Krang.

Mikey & Don, Party Planners

Ward {2}
You may look at the top card of your library any time.
You may play lands and cast Mutant, Ninja, or Turtle spells from the top of your library. If you cast a creature spell this way, that creature enters with an additional +1/+1 counter on it.

Ninja Pizza

Foods you control have "{T}, Sacrifice this artifact: Add one mana of any color."
At the beginning of your second main phase, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Leonardo, the Balance

Whenever a token you control enters, you may put a +1/+1 counter on each creature you control. Do this only once each turn.
{W}{U}{B}{R}{G}: Creatures you control gain menace, trample, and lifelink until end of turn.
Partner—Character select (You can have two commanders if both have this ability.)

Wave Goodbye

Return each creature without a +1/+1 counter on it to its owner's hand.

Super Shredder

Menace
Whenever another permanent leaves the battlefield, put a +1/+1 counter on Super Shredder.

Voracious Hydra

Trample
This creature enters with X +1/+1 counters on it.
When this creature enters, choose one —
• Double the number of +1/+1 counters on this creature.
• This creature fights target creature you don't control.

Acidic Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, destroy target artifact, enchantment, or land.

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Turtle Lair

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a Ninja or Turtle spell.
{3}, {T}: Target Ninja or Turtle can't be blocked this turn.

April O'Neil, Live on the Scene

Whenever a Mutant, Ninja, or Turtle you control enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Partner—Character select

Continue?

Choose up to four target creature cards in your graveyard that were put there from the battlefield this turn. Return them to the battlefield.

Mondrak, Glory Dominus

If one or more tokens would be created under your control, twice that many of those tokens are created instead.
{1}{W/P}{W/P}, Sacrifice two other artifacts and/or creatures: Put an indestructible counter on Mondrak. ({W/P} can be paid with either {W} or 2 life.)

Rosie Cotton of South Lane

When Rosie Cotton enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Whenever you create a token, put a +1/+1 counter on target creature you control other than Rosie Cotton.

Donatello, Gadget Master

Sneak {1}{U} (You may cast this spell for {1}{U} if you also return an unblocked attacker you control to hand during the declare blockers step. He enters tapped and attacking.)
Whenever Donatello deals combat damage to a player, create a token that's a copy of target artifact you control.

Tempestra, Dame of Games

{2}{R}, {T}, Sacrifice an artifact: Create a token that's a copy of another target creature you control, except it isn't legendary. It gains haste. Sacrifice it at the beginning of the next end step.

Splinter, Radical Rat

If a triggered ability of a Ninja creature you control triggers, that ability triggers an additional time.
{1}{U}: Target Ninja can't be blocked this turn.

Raphael, the Muscle

Double all damage that creatures you control with counters on them would deal.
When Raphael enters, create a Mutagen token.
Partner—Character select (You can have two commanders if both have this ability.)

Hidden Hideout

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity.
{2}, {T}: Target creature you control with a counter on it gains lifelink until end of turn.

Arcade Cabinet

When this artifact enters, put a +1/+1 counter on each of up to four target creatures.
{2}, {T}, Sacrifice a token: Double the number of each kind of counter on target creature.

Leonardo, Cutting Edge

Sneak {W} (You may cast this spell for {W} if you also return an unblocked attacker you control to hand during the declare blockers step. He enters tapped and attacking.)
Lifelink
Whenever you gain life, put a +1/+1 counter on Leonardo.

Level Up

Enchant creature
When this Aura enters, put a +1/+1 counter on enchanted creature.
Enchanted creature has "Whenever this creature attacks, double the number of +1/+1 counters on it. Then if it has power 10 or greater, draw a card."

Raph & Mikey, Troublemakers

Trample, haste
Whenever Raph & Mikey attack, reveal cards from the top of your library until you reveal a creature card. Put that card onto the battlefield tapped and attacking and the rest on the bottom of your library in a random order.

Raph & Leo, Sibling Rivals

Whenever Raph & Leo attack, if it's the first combat phase of the turn, untap one or two target attacking creatures. After this phase, there is an additional combat phase.

Michelangelo, Mutant BFF

Each creature you control with a counter on it can't be blocked by more than one creature.
Whenever Michelangelo enters or attacks, create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")

Baxter, Fly in the Ointment

Whenever Baxter enters or attacks, each creature you control with a counter on it gains flying until end of turn.
Whenever you draw a card, put a +1/+1 counter on Baxter.

Birds of Paradise

Leatherhead, Iron Gator

Trample, haste
Whenever Leatherhead attacks, put two +1/+1 counters on each creature you control.

Lessons from Life

Draw three cards. You may put a land card from your hand onto the battlefield tapped.

Donatello, the Brains

If one or more tokens would be created under your control, those tokens plus a Mutagen token are created instead.
Partner—Character select (You can have two commanders if both have this ability.)

Bloom Tender

Vivid — {T}: For each color among permanents you control, add one mana of that color.

Adeline, Resplendent Cathar

Vigilance
Adeline's power is equal to the number of creatures you control.
Whenever you attack, for each opponent, create a 1/1 white Human creature token that's tapped and attacking that player or a planeswalker they control.

Lita, Little Orphan Amphibian

Alliance — Whenever another creature you control enters, choose one that hasn't been chosen this turn.
• Put a +1/+1 counter on Lita.
• Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
• Scry 1.

Tendershoot Dryad

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
At the beginning of each upkeep, create a 1/1 green Saproling creature token.
Saprolings you control get +2/+2 as long as you have the city's blessing.

Dark Leo & Shredder

Sneak {W}{B}
Attacking Ninjas you control have deathtouch.
Whenever Dark Leo & Shredder deal combat damage to a player, create a 1/1 black Ninja creature token. Then if you control five or more Ninjas, that player loses half their life, rounded up.

Mikey & Leo, Chaos & Order

Whenever you put a counter on a creature you control, draw a card. This ability triggers only once each turn.

Mutagen Man, Living Ooze

Trample
Activated abilities of artifact tokens you control cost {1} less to activate.
When Mutagen Man enters, create X Mutagen tokens. (They're artifacts with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")

Technodrome

Reach, trample
This creature can't attack or block unless its power is 6 or greater.
{T}, Sacrifice another artifact: Draw a card. Put a +1/+1 counter on this creature.

Michelangelo, Improviser

Sneak {2}{G}{G} (You may cast this spell for {2}{G}{G} if you also return an unblocked attacker you control to hand during the declare blockers step. He enters tapped and attacking.)
Whenever Michelangelo deals combat damage to a player, you may put a creature card and/or a land card from your hand onto the battlefield.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Casey Jones, Back Alley Brute

Menace
Whenever Casey Jones attacks, put a +1/+1 counter on target attacking creature.
Whenever you put one or more +1/+1 counters on a creature you control, Casey Jones deals that much damage to target opponent.

Irma, Part-Time Mutant

At the beginning of combat on your turn, Irma becomes a copy of up to one other target creature you control, except her name is Irma, Part-Time Mutant and she has this ability. Then put a +1/+1 counter on her.

Raphael, the Nightwatcher

Sneak {1}{R}{R} (You may cast this spell for {1}{R}{R} if you also return an unblocked attacker you control to hand during the declare blockers step. He enters tapped and attacking.)
Attacking creatures you control have double strike.

Faeburrow Elder

Vigilance
This creature gets +1/+1 for each color among permanents you control.
{T}: For each color among permanents you control, add one mana of that color.

Coin of Mastery

Each creature you control enters with an additional +1/+1 counter on it for each mana from an artifact source spent to cast it.
{T}: Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Vigor

Trample
If damage would be dealt to another creature you control, prevent that damage. Put a +1/+1 counter on that creature for each 1 damage prevented this way.
When Vigor is put into a graveyard from anywhere, shuffle it into its owner's library.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Big Mother Mouser

This creature enters with two +1/+1 counters on it.
Whenever this creature attacks, double the number of +1/+1 counters on it.
When this creature dies, create a number of 1/1 colorless Robot artifact creature tokens equal to the number of +1/+1 counters on this creature.

Herald of Secret Streams

Creatures you control with +1/+1 counters on them can't be blocked.

Electric Seaweed

Defender, haste
When this creature enters, until end of turn, whenever another creature dies, this creature deals 1 damage to each non-Wall creature.
{T}: This creature deals 1 damage to any target.

Roadkill Rodney

Squad {3} (As an additional cost to cast this spell, you may pay {3} any number of times. When this creature enters, create that many tokens that are copies of it.)
Deathtouch
Whenever this creature deals combat damage to a player, create a Mutagen token.

Rat King, Pale Piper

Menace
Whenever Rat King or another nontoken creature you control leaves the battlefield, create a 1/1 black Rat creature token.
{2}, Sacrifice a token: Draw a card.

Splinter, the Mentor

Menace
Whenever Splinter or another nontoken creature you control leaves the battlefield, create a Mutagen token.
Partner—Character select (You can have two commanders if both have this ability.)

Heroes in a Half Shell

Vigilance, menace, trample, haste
Whenever one or more Mutants, Ninjas, and/or Turtles you control deal combat damage to a player, put a +1/+1 counter on each of those creatures and draw a card.