Lightning Mare

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

Gilded Ghoda

Whenever this creature attacks while saddled, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Shadowfax, Lord of Horses

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

Diamond Mare

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

Brightfield Mustang

Whenever this creature attacks while saddled, untap it and put a +1/+1 counter on it.
Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Bill the Pony

When Bill the Pony enters, create two Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this token: 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.

Armored Warhorse

Thundermare

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

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.)

Workhorse

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

Shield Mare

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

Clockwork Steed

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

Hipparion

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

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.)

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.

Trenching Steed

Sacrifice a land: This creature gets +0/+3 until end of turn.

Chrome Steed

Metalcraft — This creature gets +2/+2 as long as you control three or more artifacts.

Calamity, Galloping Inferno

Haste
Whenever Calamity attacks while saddled, choose a nonlegendary creature that saddled it this turn and create a tapped and attacking token that's a copy of it. Sacrifice that token at the beginning of the next end step. Repeat this process once.
Saddle 1

Akroan Horse

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

Guardian Sunmare

Ward {2}
Whenever this creature attacks while saddled, search your library for a nonland permanent card with mana value 3 or less, put it onto the battlefield, then shuffle.
Saddle 4