Captivating Unicorn

Constellation — Whenever an enchantment you control enters, tap target creature an opponent controls.

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.

Celestial Unicorn

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

Daybreak Charger

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

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.)

Merry-Go-Round

Visit — Creatures you control with power 2 or less gain horsemanship until end of turn. (They can't be blocked except by creatures with horsemanship.)

Brightmare

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

Emiel the Blessed

{3}: Exile another target creature you control, then return it to the battlefield under its owner's control.
Whenever another creature you control enters, you may pay {G/W}. If you do, put a +1/+1 counter on it. If it's a Unicorn, put two +1/+1 counters on it instead. ({G/W} can be paid with either {G} or {W}.)

Mesa Unicorn

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

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.

Ronom Unicorn

Sacrifice Ronom Unicorn: Destroy target enchantment.

Armored Warhorse

Opaline Unicorn

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.

Regal Bunnicorn

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