Carnival Hellsteed

First strike, haste
Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)

Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, untap another target creature you control.

Phyrexian Warhorse

Kicker {W} (You may pay an additional {W} as you cast this spell.)
When this creature enters, if it was kicked, create a 1/1 white Soldier creature token.
{1}, Sacrifice another creature: This creature gets +2/+1 until end of turn.

Horseshoe Crab

Zodiac Horse

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)

Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Black Carriage

Trample
This creature doesn't untap during your untap step.
Sacrifice a creature: Untap this creature. Activate only during your upkeep.

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.