Monastery Swiftspear

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Mardu Ascendancy

Whenever a nontoken creature you control attacks, create a 1/1 red Goblin creature token that's tapped and attacking.
Sacrifice Mardu Ascendancy: Creatures you control get +0/+3 until end of turn.

Swamp

Scoured Barrens

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {W} or {B}.

Utter End

Jeering Instigator

Morph {2}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Jeering Instigator is turned face up, if it's your turn, gain control of another target creature until end of turn. Untap that creature. It gains haste until end of turn.

Ride Down

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

Mardu Hordechief

Raid — When Mardu Hordechief enters, if you attacked this turn, create a 1/1 white Warrior creature token.

Wingmate Roc

Flying
Raid — When Wingmate Roc enters, if you attacked this turn, create a 3/4 white Bird creature token with flying.
Whenever Wingmate Roc attacks, you gain 1 life for each attacking creature.

Mountain

Mardu Hateblade

{B}: Mardu Hateblade gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Bloodfell Caves

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {B} or {R}.

Mardu Charm

Choose one —
• Mardu Charm deals 4 damage to target creature.
• Create two 1/1 white Warrior creature tokens. They gain first strike until end of turn.
• Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Bloodstained Mire

{T}, Pay 1 life, Sacrifice Bloodstained Mire: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

Plains

Mardu Heart-Piercer

Raid — When Mardu Heart-Piercer enters, if you attacked this turn, Mardu Heart-Piercer deals 2 damage to any target.

Hordeling Outburst

Create three 1/1 red Goblin creature tokens.

Chief of the Scale

Other Warrior creatures you control get +0/+1.

Wind-Scarred Crag

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {R} or {W}.

Ponyback Brigade

When Ponyback Brigade enters or is turned face up, create three 1/1 red Goblin creature tokens.
Morph {2}{R}{W}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Arc Lightning

Arc Lightning deals 3 damage divided as you choose among one, two, or three targets.

Mardu Roughrider

Whenever Mardu Roughrider attacks, target creature can't block this turn.

War-Name Aspirant

Raid — War-Name Aspirant enters with a +1/+1 counter on it if you attacked this turn.
War-Name Aspirant can't be blocked by creatures with power 1 or less.

Crater's Claws

Crater's Claws deals X damage to any target.
Ferocious — Crater's Claws deals X plus 2 damage instead if you control a creature with power 4 or greater.

Bring Low

Bring Low deals 3 damage to target creature. If that creature has a +1/+1 counter on it, Bring Low deals 5 damage to it instead.

Mardu Warshrieker

Raid — When Mardu Warshrieker enters, if you attacked this turn, add {R}{W}{B}.

Butcher of the Horde

Flying
Sacrifice another creature: Butcher of the Horde gains your choice of vigilance, lifelink, or haste until end of turn.

Suspension Field

When Suspension Field enters, you may exile target creature with toughness 3 or greater until Suspension Field leaves the battlefield. (That creature returns under its owner's control.)