Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Caltrops

Whenever a creature attacks, Caltrops deals 1 damage to it.

Mountain

Shock

Aether Flash

Whenever a creature enters, Aether Flash deals 2 damage to it.

Lunge

Lunge deals 2 damage to target creature and 2 damage to target player or planeswalker.

Repercussion

Whenever a creature is dealt damage, Repercussion deals that much damage to that creature's controller.

Forbidden Orchard

{T}: Add one mana of any color.
Whenever you tap Forbidden Orchard for mana, target opponent creates a 1/1 colorless Spirit creature token.

Crushing Pain

Crushing Pain deals 6 damage to target creature that was dealt damage this turn.

Incinerate

Incinerate deals 3 damage to any target. A creature dealt damage this way can't be regenerated this turn.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Lava Spike

Lava Spike deals 3 damage to target player or planeswalker.

Furnace of Rath

If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.