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.

Trusted Pegasus

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever Trusted Pegasus attacks, target attacking creature without flying gains flying until end of turn.

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.

Shepherd of the Clouds

Flying, vigilance
When Shepherd of the Clouds enters, return target permanent card with mana value 3 or less from your graveyard to your hand. Return that card to the battlefield instead if you control a Mount.

Arcane Signet

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

Armored Pegasus

Ondu Skyruins

Ondu Skyruins enters tapped.
{T}: Add {W}.

Ondu Inversion

Ondu Inversion // Ondu Skyruins

Concordia Pegasus

Arborea Pegasus

Flying
When Arborea Pegasus enters, target creature gets +1/+1 and gains flying until end of turn.

Mass Calcify

Steadfast Unicorn

{3}{W}: Creatures you control get +1/+1 and gain vigilance until end of turn. Activate only during your turn. (Attacking doesn't cause them to tap.)

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Sol Ring

Valkyrie's Call

Whenever a nontoken, non-Angel creature you control dies, return that card to the battlefield under its owner's control with a +1/+1 counter on it. It has flying and is an Angel in addition to its other types.

Blessed Sanctuary

Prevent all noncombat damage that would be dealt to you and creatures you control.
Whenever a nontoken creature you control enters, create a 2/2 white Unicorn creature token.

Diamond Mare

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

Sunmane Pegasus

Flying
{1}{W}: Sunmane Pegasus gains vigilance and lifelink until end of turn. (Attacking doesn't cause it to tap. Damage dealt by it also causes you to gain that much life.)

Pegasus Courser

Flying
Whenever Pegasus Courser attacks, another target attacking creature gains flying until end of turn.

Storm Herd

Create X 1/1 white Pegasus creature tokens with flying, where X is your life total.

Regal Bunnicorn

Regal Bunnicorn's power and toughness are each equal to the number of nonland permanents you control.

Thurid, Mare of Destiny

Flying, lifelink
Whenever you cast a Pegasus, Unicorn, or Horse creature spell, copy it. (The copy becomes a token.)
Other Pegasi, Unicorns, and Horses you control get +1/+1.

Starnheim Courser

Flying
Artifact and enchantment spells you cast cost {1} less to cast.

Rider in Need

Create a 2/2 white Knight creature token with vigilance. (Then exile this card. You may cast the creature later from exile.)

Lonesome Unicorn

Lonesome Unicorn // Rider in Need

Brightmare

When Brightmare enters, tap up to one target creature. You gain life equal to that creature's power.

Neighborhood Guardian

Whenever another creature you control with power 2 or less enters, target creature you control gets +1/+1 until end of turn.

Celestial Unicorn

Whenever you gain life, put a +1/+1 counter on Celestial Unicorn.

Honor of the Pure

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

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.)

Loyal Pegasus

Flying
Loyal Pegasus can't attack or block alone.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Sungrace Pegasus

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Intangible Virtue

Creature tokens you control get +1/+1 and have vigilance.

Boreas Charger

Flying
When Boreas Charger leaves the battlefield, choose an opponent who controls more lands than you. Search your library for a number of Plains cards equal to the difference, reveal those cards, put one of them onto the battlefield tapped and the rest into your hand, then shuffle.

Rescue the Foal

Exile target creature you control, then return that card to the battlefield under its owner's control. (Then exile this card. You may cast the creature later from exile.)

Pegasus Guardian

Flying
At the beginning of your end step, if a permanent you controlled left the battlefield this turn, create a 1/1 white Pegasus creature token with flying.

Pegasus Guardian // Rescue the Foal

Leyline of Hope

If Leyline of Hope is in your opening hand, you may begin the game with it on the battlefield.
If you would gain life, you gain that much life plus 1 instead.
As long as you have at least 7 life more than your starting life total, creatures you control get +2/+2.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Daybreak Charger

When Daybreak Charger enters, target creature gets +2/+0 until end of turn.

Opaline Unicorn

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.

Phyrexian Pegasus

Flying
Whenever Phyrexian Pegasus attacks, another target attacking creature without flying gains flying until end of turn.

Plains

Nyxborn Unicorn

Bestow {3}{W} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.)
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Enchanted creature gets +2/+2 and has mentor.

Armored Warhorse

Splendor Mare

Lifelink
Cycling {1}{W} ({1}{W}, Discard this card: Draw a card.)
When you cycle Splendor Mare, put a lifelink counter on target creature you control.

Loyal Unicorn

Vigilance
Lieutenant — At the beginning of combat on your turn, if you control your commander, prevent all combat damage that would be dealt to creatures you control this turn. Other creatures you control gain vigilance until end of turn.