Rodeo Pyromancers

Whenever you cast your first spell each turn, add {R}{R}.

Mountain

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.)

Aloe Alchemist

Trample
When Aloe Alchemist becomes plotted, target creature gets +3/+2 and gains trample until end of turn.
Plot {1}{G} (You may pay {1}{G} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Forest

Longhorn Sharpshooter

Reach
When Longhorn Sharpshooter becomes plotted, it deals 2 damage to any target.
Plot {3}{R} (You may pay {3}{R} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Edge of Autumn

If you control four or fewer lands, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Cycling—Sacrifice a land. (Sacrifice a land, Discard this card: Draw a card.)

Ride Down

Destroy target blocking creature. Creatures that were blocked by that creature this combat gain trample until end of turn.

Rally for the Throne

Create two 1/1 white Human creature tokens.
Adamant — If at least three white mana was spent to cast this spell, you gain 1 life for each creature you control.

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.)

Trained Arynx

Whenever Trained Arynx attacks while saddled, it gains first strike until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
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.)

Great Train Heist

Spree (Choose one or more additional costs.)
+ {2}{R} — Untap all creatures you control. If it's your combat phase, there is an additional combat phase after this phase.
+ {2} — Creatures you control get +1/+0 and gain first strike until end of turn.
+ {R} — Choose target opponent. Whenever a creature you control deals combat damage to that player this turn, create a tapped Treasure token.

Silver Deputy

When Silver Deputy enters, you may search your library for a basic land card or a Desert card, reveal it, then shuffle and put it on top.
{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery.

Bruse Tarl, Roving Rancher

Oxen you control have double strike.
Whenever Bruse Tarl, Roving Rancher enters or attacks, exile the top card of your library. If it's a land card, create a 2/2 white Ox creature token. Otherwise, you may cast it until the end of your next turn.

Discerning Peddler

When Discerning Peddler enters, you may discard a card. If you do, draw a card.

Bovine Intervention

Destroy target artifact or creature. Its controller creates a 2/2 white Ox creature token.

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."

Sterling Keykeeper

Claim Jumper

Vigilance
When Claim Jumper enters, if an opponent controls more lands than you, you may search your library for a Plains card and put it onto the battlefield tapped. Then if an opponent controls more lands than you, repeat this process once. If you search your library this way, shuffle.

Vengeful Townsfolk

Whenever one or more other creatures you control die, put a +1/+1 counter on Vengeful Townsfolk.

Pillarfield Ox

Spinewoods Armadillo

Reach
Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)
{1}{G}, Discard Spinewoods Armadillo: Search your library for a basic land card or a Desert card, reveal it, put it into your hand, then shuffle. You gain 3 life.

Luxurious Locomotive

Whenever Luxurious Locomotive attacks, create a Treasure token for each creature that crewed it this turn. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")
Crew 1. Activate only once each turn. (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Giant Beaver

Vigilance
Whenever Giant Beaver attacks while saddled, put a +1/+1 counter on target creature that saddled it this turn.
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.)

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.)

Rambling Possum

Whenever Rambling Possum 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.)

Hardbristle Bandit

{T}: Add one mana of any color.
Whenever you commit a crime, untap Hardbristle Bandit. This ability triggers only once each turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Giant Ox

Giant Ox crews Vehicles using its toughness rather than its power.

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.

Thunder Salvo

Thunder Salvo deals X damage to target creature, where X is 2 plus the number of other spells you've cast this turn.

Prickly Pair

When Prickly Pair 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."

Mischievous Pup

Flash
When Mischievous Pup enters, return up to one other target permanent you control to its owner's hand.

Plains

Full Steam Ahead

Until end of turn, each creature you control gets +2/+2 and gains trample and "This creature can't be blocked by more than one creature."