Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Wurmcoil Engine

Deathtouch, lifelink
When this creature dies, create a 3/3 colorless Phyrexian Wurm artifact creature token with deathtouch and a 3/3 colorless Phyrexian Wurm artifact creature token with lifelink.

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga gains "{T}: Add {C}."
II — This Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This token gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Donnie & April, Adorkable Duo

When Donnie & April enter, choose one or both. Each mode must target a different player.
• Target player draws two cards.
• Target player returns an artifact, instant, or sorcery card from their graveyard to their hand.

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.

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Dark Depths

Dark Depths enters with ten ice counters on it.
{3}: Remove an ice counter from Dark Depths.
When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

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.

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.

Turtles in Time

Return all creatures to their owners' hands. Each player may shuffle their hand and graveyard into their library, then each player who does draws seven cards.
Exile Turtles in Time.

Turtle Van

Whenever this Vehicle attacks, put a +1/+1 counter on target creature that crewed it this turn. Then if that creature is a Mutant, Ninja, or Turtle, double the number of +1/+1 counters on it.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

April O'Neil, Hacktivist

At the beginning of your end step, draw a card for each card type among spells you've cast this turn.

Thespian's Stage

{T}: Add {C}.
{2}, {T}: This land becomes a copy of target land, except it has this ability.

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.

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.")

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

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.

Cryptothrall

Protector — Other artifact creatures you control have hexproof.

Island

Command Tower

Cloud Key

As this artifact enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Donatello, Mutant Mechanic

{T}: Put three +1/+1 counters on target artifact you control. If it isn't a creature, it becomes a 0/0 Robot creature in addition to its other types. Activate only as a sorcery.
Whenever an artifact you control is put into a graveyard from the battlefield, if it had counters on it, put those counters on up to one target artifact or creature you control.

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.

Canoptek Scarab Swarm

Flying
Feeder Mandibles — When this creature enters, exile target player's graveyard. For each artifact or land card exiled this way, create a 1/1 colorless Insect artifact creature token with flying.

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Return target artifact card from your graveyard to your hand.

Krang, Utrom Warlord

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

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Sol Ring

Wave Goodbye

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

Donatello, Way with Machines

Flying
Whenever an artifact you control enters, put a +1/+1 counter on Donatello.

Shadowspear

Equipped creature gets +1/+1 and has trample and lifelink.
{1}: Permanents your opponents control lose hexproof and indestructible until end of turn.
Equip {2}

Karn, Legacy Reforged

Karn's power and toughness are each equal to the greatest mana value among artifacts you control.
At the beginning of your upkeep, add {C} for each artifact you control. This mana can't be spent to cast nonartifact spells. Until end of turn, you don't lose this mana as steps and phases end.

Canoptek Wraith

Wraith Form — This creature can't be blocked.
Transdimensional Scout — When this creature deals combat damage to a player, you may pay {3} and sacrifice it. If you do, choose a land you control. Then search your library for up to two basic land cards which have the same name as the chosen land, put them onto the battlefield tapped, then shuffle.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Sceptre of Eternal Glory

{T}: Add one mana of any color.
{T}: Add three mana of any one color. Activate only if you control three or more lands with the same name.

The Ooze

Whenever a creature you control with a +1/+1 counter on it leaves the battlefield, create a Mutagen token for each +1/+1 counter on it. (A Mutagen token is an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")
{T}: Exile target card from a graveyard. Create a Mutagen token.

Donatello, Rad Scientist

Vigilance (Attacking doesn't cause this creature to tap.)
When Donatello enters, tap up to three target creatures your opponents control. Put a stun counter on each of them. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

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.")

Darksteel Citadel

Here Comes a New Hero!

Target player draws X cards. Create a token that's a copy of up to one target creature with mana value X or less.