Your companion exudes an air of ferocity as it attacks, which lends agility and allows you both to react to your foe's movements.

Encounter   ✦     Beast, Martial
Standard Action      Melee beast 1

Target: One creature

Attack: Beast's attack bonus vs. AC

Hit: 2[B] + your beast's Strength modifier damage. If you and your beast companion are flanking the target, the first time the target moves or shifts before the end of your next turn, you and your beast companion can shift 3 squares as an immediate reaction.

Published in Dragon Magazine 387, page(s) 45.