Bloodline Pretender

Changeling (This card is every creature type.)
As Bloodline Pretender enters, choose a creature type.
Whenever another creature you control of the chosen type enters, put a +1/+1 counter on Bloodline Pretender.

Crested Sunmare

Other Horses you control have indestructible.
At the beginning of each end step, if you gained life this turn, create a 5/5 white Horse creature token.

Irregular Cohort

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

Primal Clay

As Primal Clay enters, it becomes your choice of a 3/3 artifact creature, a 2/2 artifact creature with flying, or a 1/6 Wall artifact creature with defender in addition to its other types. (A creature with defender can't attack.)

War-Spike Changeling

Changeling (This card is every creature type.)
{R}: War-Spike Changeling gains first strike until end of turn.

Shadowfax, Lord of Horses

Horses you control have haste. (They can attack and {T} as soon as they come under your control.)
Whenever Shadowfax, Lord of Horses attacks, you may put a creature card with lesser power from your hand onto the battlefield tapped and attacking.

Changeling Hero

Changeling (This card is every creature type.)
Champion a creature (When this enters, 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.)

Shared Animosity

Whenever a creature you control attacks, it gets +1/+0 until end of turn for each other attacking creature that shares a creature type with it.

Changeling Sentinel

Changeling (This card is every creature type.)
Vigilance

Keleth, Sunmane Familiar

Whenever a commander you control attacks, put a +1/+1 counter on it.
Partner (You can have two commanders if both have partner.)

Impostor of the Sixth Pride

Changeling (This card is every creature type.)

Battlegate Mimic

Whenever you cast a spell that's both red and white, Battlegate Mimic has base power and toughness 4/2 until end of turn and gains first strike until end of turn.

Dwarven Pony

{1}{R}, {T}: Target Dwarf creature gains mountainwalk until end of turn. (It can't be blocked as long as defending player controls a Mountain.)

Death-Mask Duplicant

Imprint — {1}: Exile target creature card from your graveyard.
As long as a card exiled with Death-Mask Duplicant has flying, Death-Mask Duplicant has flying. The same is true for fear, first strike, double strike, haste, landwalk, protection, and trample.

Bill the Pony

When Bill the Pony enters, create two Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Sacrifice a Food: Until end of turn, target creature you control assigns combat damage equal to its toughness rather than its power.

Shields of Velis Vel

Changeling (This card is every creature type.)
Creatures target player controls get +0/+1 and gain all creature types until end of turn.

Hipparion

Hipparion can't block creatures with power 3 or greater unless you pay {1}.

Bronze Horse

Trample
As long as you control another creature, prevent all damage that would be dealt to Bronze Horse by spells that target it.

Blades of Velis Vel

Changeling (This card is every creature type.)
Up to two target creatures each get +2/+0 and gain all creature types until end of turn.

Fire-Belly Changeling

Changeling (This card is every creature type.)
{R}: Fire-Belly Changeling gets +1/+0 until end of turn. Activate no more than twice each turn.

Brightling

{W}: Brightling gains vigilance until end of turn.
{W}: Brightling gains lifelink until end of turn.
{W}: Return Brightling to its owner's hand.
{1}: Brightling gets +1/-1 or -1/+1 until end of turn.

Shield Mare

Shield Mare can't be blocked by red creatures.
When Shield Mare enters or becomes the target of a spell or ability an opponent controls, you gain 3 life.

Workhorse

Workhorse enters with four +1/+1 counters on it.
Remove a +1/+1 counter from Workhorse: Add {C}.

Diamond Mare

As Diamond Mare enters, choose a color.
Whenever you cast a spell of the chosen color, you gain 1 life.

Crib Swap

Changeling (This card is every creature type.)
Exile target creature. Its controller creates a 1/1 colorless Shapeshifter creature token with changeling.

Trenching Steed

Sacrifice a land: Trenching Steed gets +0/+3 until end of turn.

Chrome Steed

Metalcraft — Chrome Steed gets +2/+2 as long as you control three or more artifacts.

Taurean Mauler

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

Avian Changeling

Changeling (This card is every creature type.)
Flying

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

Armored Warhorse

Proteus Machine

Morph {0} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Proteus Machine is turned face up, it becomes the creature type of your choice. (This effect lasts indefinitely.)

Akroan Horse

Defender
When Akroan Horse enters, an opponent gains control of it.
At the beginning of your upkeep, each opponent creates a 1/1 white Soldier creature token.

Metallic Mimic

As Metallic Mimic enters, choose a creature type.
Metallic Mimic is the chosen type in addition to its other types.
Each other creature you control of the chosen type enters with an additional +1/+1 counter on it.

Changeling Berserker

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

Clockwork Steed

Clockwork Steed enters with four +1/+0 counters on it.
Clockwork Steed can't be blocked by artifact creatures.
At end of combat, if Clockwork Steed attacked or blocked this combat, remove a +1/+0 counter from it.
{X}, {T}: Put up to X +1/+0 counters on Clockwork Steed. This ability can't cause the total number of +1/+0 counters on Clockwork Steed to be greater than four. Activate only during your upkeep.

The Prismatic Piper

If The Prismatic Piper is your commander, choose a color before the game begins. The Prismatic Piper is the chosen color.
Partner (You can have two commanders if both have partner.)

Lightning Mare

This spell can't be countered.
Lightning Mare can't be blocked by blue creatures.
{1}{R}: Lightning Mare gets +1/+0 until end of turn.

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Thundermare

Haste (This creature can attack and {T} as soon as it comes under your control.)
When Thundermare enters, tap all other creatures.

Torchling

{R}: Untap Torchling.
{R}: Target creature blocks Torchling this turn if able.
{R}: Change the target of target spell that targets only Torchling.
{1}: Torchling gets +1/-1 until end of turn.
{1}: Torchling gets -1/+1 until end of turn.

Ebony Horse

{2}, {T}: Untap target attacking creature you control. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

Duplicant

Imprint — When Duplicant enters, you may exile target nontoken creature.
As long as a card exiled with Duplicant is a creature card, Duplicant has the power, toughness, and creature types of the last creature card exiled with Duplicant. It's still a Shapeshifter.