Gloryheath Lynx

Lifelink
Whenever this creature attacks while saddled, search your library for a basic Plains card, reveal it, put it into your hand, then shuffle.
Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Cloudspire Captain

Mounts and Vehicles you control get +1/+1.
This creature saddles Mounts and crews Vehicles as though its power were 2 greater.

Shepherd of the Clouds

Flying, vigilance
When this creature 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.

Ornery Tumblewagg

At the beginning of combat on your turn, put a +1/+1 counter on target creature.
Whenever this creature attacks while saddled, double the number of +1/+1 counters on target creature.
Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Rambling Possum

Whenever this creature attacks while saddled, it gets +1/+2 until end of turn. Then you may return any number of creatures that saddled it this turn to their owner's hand.
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.)

District Mascot

This creature enters with a +1/+1 counter on it.
{1}{G}, Remove two +1/+1 counters from this creature: Destroy target artifact.
Whenever this creature attacks while saddled, put a +1/+1 counter on it.
Saddle 1

Wylie Duke, Atiin Hero

Vigilance
Whenever Wylie Duke becomes tapped, you gain 1 life and draw a card.

Miriam, Herd Whisperer

During your turn, Mounts and Vehicles you control have hexproof.
Whenever a Mount or Vehicle you control attacks, put a +1/+1 counter on it.

Seraphic Steed

First strike, lifelink
Whenever this creature attacks while saddled, create a 3/3 white Angel creature token with flying.
Saddle 4 (Tap any number of other creatures you control with total power 4 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Unswerving Sloth

Whenever this creature attacks while saddled, it gains indestructible until end of turn. Untap all creatures you control.
Saddle 4 (Tap any number of other creatures you control with total power 4 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Frontier Seeker

When this creature enters, look at the top five cards of your library. You may reveal a Mount creature card or a Plains card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Bulwark Ox

Whenever this creature attacks while saddled, put a +1/+1 counter on target creature.
Sacrifice this creature: Creatures you control with counters on them gain hexproof and indestructible until end of turn.
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.)

Lagorin, Soul of Alacria

Flying
Whenever Lagorin attacks while saddled, put a +1/+1 counter on each of up to two target Mounts and/or Vehicles.
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.)

Fortune, Loyal Steed

When Fortune enters, scry 2.
Whenever Fortune attacks while saddled, at end of combat, exile it and up to one creature that saddled it this turn, then return those cards to the battlefield under their owner's control.
Saddle 1

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

Bounding Felidar

Whenever this creature attacks while saddled, put a +1/+1 counter on each other creature you control. You gain 1 life for each of those creatures.
Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Caradora, Heart of Alacria

When Caradora enters, you may search your library for a Mount or Vehicle card, reveal it, put it into your hand, then shuffle.
If one or more +1/+1 counters would be put on a creature or Vehicle you control, that many plus one +1/+1 counters are put on it instead.

Congregation Gryff

Flying, lifelink
Whenever this creature attacks while saddled, it gets +X/+X until end of turn, where X is the number of Mounts you control.
Saddle 3 (Tap any number of other creatures you control with total power 3 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Interface Ace

This creature saddles Mounts and crews Vehicles using its toughness rather than its power.
Whenever this creature becomes tapped during your turn, untap it. This ability triggers only once each turn.