Dragon Whisperer

{R}: Dragon Whisperer gains flying until end of turn.
{1}{R}: Dragon Whisperer gets +1/+0 until end of turn.
Formidable — {4}{R}{R}: Create a 4/4 red Dragon creature token with flying. Activate only if creatures you control have total power 8 or greater.

Flametongue Kavu

When Flametongue Kavu enters, it deals 4 damage to target creature.

Flamewake Phoenix

Flying, haste
This creature attacks each combat if able.
At the beginning of combat on your turn, if you control a creature with power 4 or greater, you may pay {R}. If you do, return this card from your graveyard to the battlefield.

Vexing Devil

When Vexing Devil enters, any opponent may have it deal 4 damage to them. If a player does, sacrifice Vexing Devil.

Mountain

Stampede Rider

Trample
At the beginning of each combat, if you control a creature with power 4 or greater, Stampede Rider gets +1/+1 until end of turn.

Flames of the Raze-Boar

Flames of the Raze-Boar deals 4 damage to target creature an opponent controls. Then Flames of the Raze-Boar deals 2 damage to each other creature that player controls if you control a creature with power 4 or greater.

Anax, Hardened in the Forge

Anax's power is equal to your devotion to red. (Each {R} in the mana costs of permanents you control counts toward your devotion to red.)
Whenever Anax or another nontoken creature you control dies, create a 1/1 red Satyr creature token with "This creature can't block." If the creature had power 4 or greater, create two of those tokens instead.

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Fall of the Hammer

Target creature you control deals damage equal to its power to another target creature.

Thriving Bluff

Thriving Bluff enters tapped. As it enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Atarka Pummeler

Formidable — {3}{R}{R}: Creatures you control gain menace until end of turn. Activate only if creatures you control have total power 8 or greater. (They can't be blocked except by two or more creatures.)

Volcanic Salvo

This spell costs {X} less to cast, where X is the total power of creatures you control.
Volcanic Salvo deals 6 damage to each of up to two target creatures and/or planeswalkers.

Furious Rise

At the beginning of your end step, if you control a creature with power 4 or greater, exile the top card of your library. You may play that card until you exile another card with Furious Rise.