"We are the heart of the wild, the fire in its eyes, and the howl in its throat. Come, join the battle to which you were born."
—Kroshkar, Gruul shaman

The List

Gruul War Chant

Attacking creatures you control get +1/+0 and have menace.

Modern Masters 2017

Conspiracy: Take the Crown

Attacking creatures you control get +1/+0 and have menace. (They can't be blocked except by two or more creatures.)

Dragon's Maze

Each attacking creature you control gets +1/+0 and can't be blocked except by two or more creatures.