Requisition Raid

Spree (Choose one or more additional costs.)
+ {1} — Destroy target artifact.
+ {1} — Destroy target enchantment.
+ {1} — Put a +1/+1 counter on each creature target player controls.

Conduit Pylons

When Conduit Pylons enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Steer Clear

Steer Clear deals 2 damage to target attacking or blocking creature. Steer Clear deals 4 damage to that creature instead if you controlled a Mount as you cast this spell.

Seraphic Steed

First strike, lifelink
Whenever Seraphic Steed 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.)

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.

Wylie Duke, Atiin Hero

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

Frontier Seeker

When Frontier Seeker 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.

Drover Grizzly

Whenever Drover Grizzly attacks while saddled, creatures you control gain trample 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.)

Bridled Bighorn

Vigilance
Whenever Bridled Bighorn attacks while saddled, create a 1/1 white Sheep creature token.
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.)

Forest

Bucolic Ranch

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a Mount spell.
{3}, {T}: Look at the top card of your library. If it's a Mount card, you may reveal it and put it into your hand. If you don't put it into your hand, you may put it on the bottom of your library.

Dance of the Tumbleweeds

Spree (Choose one or more additional costs.)
+ {1} — Search your library for a basic land card or a Desert card, put it onto the battlefield, then shuffle.
+ {3} — Create an X/X green Elemental creature token, where X is the number of lands you control.

Creosote Heath

Creosote Heath enters tapped.
When Creosote Heath enters, it deals 1 damage to target opponent.
{T}: Add {G} or {W}.

Congregation Gryff

Flying, lifelink
Whenever Congregation Gryff 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.)

Plains

Lassoed by the Law

When Lassoed by the Law enters, exile target nonland permanent an opponent controls until Lassoed by the Law leaves the battlefield.
When Lassoed by the Law enters, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."

Throw from the Saddle

Target creature you control gets +1/+1 until end of turn. Put a +1/+1 counter on it instead if it's a Mount. Then it deals damage equal to its power to target creature you don't control.

Rustler Rampage

Spree (Choose one or more additional costs.)
+ {1} — Untap all creatures target player controls.
+ {1} — Target creature gains double strike until end of turn.