Izzet Signet

Changeling Berserker

Changeling (This card is every creature type.)
Haste
Champion a creature (When this enters the battlefield, sacrifice it unless you exile another creature you control. When this leaves the battlefield, that card returns to the battlefield.)

Universal Automaton

Changeling (This card is every creature type.)

Gemhide Sliver

All Slivers have "{T}: Add one mana of any color."

Valiant Changeling

This spell costs {1} less to cast for each creature type among creatures you control. This effect can't reduce the amount of mana this spell costs by more than {5}.
Changeling (This card is every creature type.)
Double strike

Shapesharer

Changeling (This card is every creature type.)
{2}{U}: Target Shapeshifter becomes a copy of target creature until your next turn.

Reaper King

({2/W} can be paid with any two mana or with {W}. This card's mana value is 10.)
Other Scarecrow creatures you control get +1/+1.
Whenever another Scarecrow enters the battlefield under your control, destroy target permanent.

Chameleon Colossus

Changeling (This card is every creature type.)
Protection from black
{2}{G}{G}: Chameleon Colossus gets +X/+X until end of turn, where X is its power.

Command Tower

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

Boros Signet

Forest

Gruul Signet

Rakdos Signet

Irregular Cohort

Changeling (This card is every creature type.)
When Irregular Cohort enters the battlefield, create a 2/2 colorless Shapeshifter creature token with changeling.

Changeling Outcast

Changeling (This card is every creature type.)
Changeling Outcast can't block and can't be blocked.

The First Sliver

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Sliver spells you cast have cascade.

Graveshifter

Changeling (This card is every creature type.)
When Graveshifter enters the battlefield, you may return target creature card from your graveyard to your hand.

Impostor of the Sixth Pride

Dimir Signet

Unsettled Mariner

Changeling (This card is every creature type.)
Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Azorius Signet

Birthing Boughs

{4}, {T}: Create a 2/2 colorless Shapeshifter creature token with changeling. (It has every creature type.)

Crystalline Sliver

All Slivers have shroud. (They can't be the targets of spells or abilities.)

Swamp

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters the battlefield, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Venomous Changeling

Changeling (This card is every creature type.)
Deathtouch

Manaweft Sliver

Sliver creatures you control have "{T}: Add one mana of any color."

Taurean Mauler

Changeling (This card is every creature type.)
Whenever an opponent casts a spell, you may put a +1/+1 counter on Taurean Mauler.

Amoeboid Changeling

Changeling (This card is every creature type.)
{T}: Target creature gains all creature types until end of turn.
{T}: Target creature loses all creature types until end of turn.

Plains

Skeletal Changeling

Changeling (This card is every creature type.)
{1}{B}: Regenerate Skeletal Changeling.

Harmonic Sliver

All Slivers have "When this permanent enters the battlefield, destroy target artifact or enchantment."

Opaline Sliver

All Slivers have "Whenever this permanent becomes the target of a spell an opponent controls, you may draw a card."

Island

Simic Signet

Sliver Overlord

{3}: Search your library for a Sliver card, reveal that card, put it into your hand, then shuffle.
{3}: Gain control of target Sliver. (This effect lasts indefinitely.)

Arcane Signet

Changeling Hero

Changeling (This card is every creature type.)
Champion a creature (When this enters the battlefield, sacrifice it unless you exile another creature you control. When this leaves the battlefield, that card returns to the battlefield.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Mothdust Changeling

Changeling (This card is every creature type.)
Tap an untapped creature you control: Mothdust Changeling gains flying until end of turn.

Changeling Titan

Changeling (This card is every creature type.)
Champion a creature (When this enters the battlefield, sacrifice it unless you exile another creature you control. When this leaves the battlefield, that card returns to the battlefield.)

Golgari Signet

Crypt Sliver

All Slivers have "{T}: Regenerate target Sliver."

The Ur-Dragon

Eminence — As long as The Ur-Dragon is in the command zone or on the battlefield, other Dragon spells you cast cost {1} less to cast.
Flying
Whenever one or more Dragons you control attack, draw that many cards, then you may put a permanent card from your hand onto the battlefield.

Diffusion Sliver

Whenever a Sliver creature you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}.