Blech, Loafing Pest

Whenever you gain life, put a +1/+1 counter on each Pest, Bat, Insect, Snake, and Spider you control.

Planar Engineering

Sacrifice two lands. Search your library for four basic land cards, put them onto the battlefield tapped, then shuffle.

Turncoat Kunoichi

Sneak {2}{W}{B} (You may cast this spell for {2}{W}{B} if you also return an unblocked attacker you control to hand during the declare blockers step. It enters tapped and attacking.)
When this creature enters, choose target creature an opponent controls. Exile that creature until this creature leaves the battlefield. If this creature's sneak cost was paid, instead exile the chosen creature.

Krang, Master Mind

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
When Krang enters, if you have fewer than four cards in hand, draw cards equal to the difference.
Krang gets +1/+0 for each other artifact you control.

Leonardo, Leader in Blue

Sneak {3}{W}{W} (You may cast this spell for {3}{W}{W} if you also return an unblocked attacker you control to hand during the declare blockers step. He enters tapped and attacking.)
When Leonardo enters, if his sneak cost was paid, creatures you control get +2/+0 until end of turn.
{1}{W}: Leonardo gains first strike until end of turn.

Lord Dregg, Insect Invader

Flying
Disappear — At the beginning of your end step, if a permanent left the battlefield under your control this turn, create a 1/1 black Insect Warrior creature token with flying.
{3}{G}, Sacrifice a token: Draw a card.

Splinter, Radical Rat

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

Seize the Spoils

As an additional cost to cast this spell, discard a card.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

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.

Pizza Face, Gastromancer

When Pizza Face enters, create a Food token.
Disappear — At the beginning of your end step, if a permanent left the battlefield under your control this turn, put three +1/+1 counters on up to one other target artifact or creature. If it isn't a creature, it becomes a 0/0 Mutant creature in addition to its other types.
{10}, {T}, Sacrifice Pizza Face: You gain 15 life.

Cauldron of Essence

Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.
{1}{B}{G}, {T}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to that card's mana value.

Grave Researcher

At the beginning of your upkeep, surveil 1. Then if there are three or more creature cards in your graveyard, this creature becomes prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Grave Researcher // Reanimate

Sign in Blood

Target player draws two cards and loses 2 life.

Scheming Silvertongue

Flying, lifelink
At the beginning of your second main phase, if you gained 2 or more life this turn, this creature becomes prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Scheming Silvertongue // Sign in Blood

Chelonian Tackle

Target creature you control gets +0/+10 until end of turn. Then it fights up to one target creature an opponent controls. (Each deals damage equal to its power to the other.)

The Last Ronin'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.)
Create three 1/1 white Ninja Turtle Spirit creature tokens. If this spell's sneak cost was paid, they enter tapped and attacking.

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, Sewer Samurai

Sneak {2}{W}{W}
Double strike
During your turn, you may cast creature spells with power or toughness 1 or less from your graveyard. If you cast a spell this way, that creature enters with a finality counter on it. (If a creature with a finality counter on it would die, exile it instead.)

Madame Null, Power Broker

Deathtouch
Whenever another creature you control enters, you may pay life equal to its power. If you do, put that many +1/+1 counters on it.

Ian Chesterton

Science Teacher — Each Saga spell you cast has replicate. The replicate cost is equal to its mana cost. (When you cast that Saga, copy it for each time you paid its replicate cost. Copies of Saga spells become tokens.)
Doctor's companion (You can have two commanders if the other is the Doctor.)

Flashback

Target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Tegan Jovanka

Brave Heart — Whenever you attack, target attacking historic creature gets +1/+1 and gains indestructible until end of turn. (Artifacts, legendaries, and Sagas are historic.)
Doctor's companion (You can have two commanders if the other is the Doctor.)

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.