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.

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's Technique

Sneak {1}{W} (You may cast this spell for {1}{W} if you also return an unblocked attacker you control to hand during the declare blockers step.)
Return one or two target creature cards each with mana value 3 or less from your graveyard to the battlefield.

The Neutrinos

Flying
Alliance — Whenever another creature you control enters, The Neutrinos get +1/+0 until end of turn.
Whenever The Neutrinos attack, exile up to one target creature you own, then return it to the battlefield under your control tapped and attacking.

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.

Chrome Dome

Other artifact creatures you control get +1/+0.
{5}: Create a token that's a copy of another target artifact you control. That token gains haste. Sacrifice it at the beginning of the next end step.

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.

Krang, Utrom Warlord

Flying, trample, indestructible, haste
Other artifact creatures you control have flying, trample, indestructible, and haste.

Kitsune's Technique

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.)
Target opponent mills half their library, rounded up.

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.

Super Shredder

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

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.

Raphael, Ninja Destroyer

Raphael must be blocked if able.
Enrage — Whenever Raphael is dealt damage, add that much {R}. Until end of turn, you don't lose this mana as steps and phases end.