Prerequisite: Ranger, Beast Mastery class feature (serpent)
Benefit: Your beast companion gains a +2 bonus to saving throws.
While your beast companion acts independently, it need not move adjacent to you but must remain within 10 squares of you.
In addition, if it hits a creature with a melee basic attack, that creature is also immobilized until the end of the creature’s next turn.
Published in Martial Power 2, page(s) 132.