Take Up the Shield

Put a +1/+1 counter on target creature. It gains lifelink and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Wanted Griffin

Flying
When Wanted Griffin dies, 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."

Form a Posse

Create X 1/1 red Mercenary creature tokens with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."

Plains

Eriette's Lullaby

Destroy target tapped creature. You gain 2 life.

Ertha Jo, Frontier Mentor

When Ertha Jo, Frontier Mentor 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."
Whenever you activate an ability that targets a creature or player, copy that ability. You may choose new targets for the copy.

Ferocification

At the beginning of combat on your turn, choose one —
• Target creature you control gets +2/+0 until end of turn.
• Target creature you control gains menace and haste until end of turn.

Mine Raider

Trample
When Mine Raider enters, if you control another outlaw, create a Treasure token. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws. A Treasure token is an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Mountain

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.

Quick Draw

Target creature you control gets +1/+1 and gains first strike until end of turn. Creatures target opponent controls lose first strike and double strike until end of turn.

Reckless Lackey

First strike, haste
{2}{R}, Sacrifice Reckless Lackey: Draw a card and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Highway Robbery

You may discard a card or sacrifice a land. If you do, draw two cards.
Plot {1}{R} (You may pay {1}{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.)

Outlaw Medic

Lifelink
When Outlaw Medic dies, draw a card.

Hellspur Posse Boss

Other outlaws you control have haste. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
When Hellspur Posse Boss enters, create two 1/1 red Mercenary creature tokens with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."