Bulk Up

Double target creature's power until end of turn.
Flashback {4}{R}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Red Dragon

Flying
Fire Breath — When this creature enters, it deals 4 damage to each opponent.

Ruby Medallion

Red spells you cast cost {1} less to cast.

Crackle with Power

Crackle with Power deals five times X damage to each of up to X targets.

The Reaver Cleaver

Equipped creature gets +1/+1 and has trample and "Whenever this creature deals combat damage to a player or planeswalker, create that many Treasure tokens."
Equip {3}

Aggravated Assault

{3}{R}{R}: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.

Reverberate

Copy target instant or sorcery spell. You may choose new targets for the copy.

Iron Myr

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Mountain

Teeterpeak Ambusher

{2}{R}: This creature gets +2/+0 until end of turn.

Run Amok

Target attacking creature gets +3/+3 and gains trample until end of turn.

Deflecting Swat

If you control a commander, you may cast this spell without paying its mana cost.
You may choose new targets for target spell or ability.