Dorsal Deflection⟲Trigger The stegosaurus is targeted with a melee attack.
Effect The stegosaurus leans its dorsal plates into the attack, gaining a +2 circumstance bonus to its AC against the triggering attack. If the attack misses, the stegosaurus Steps after the attack.
Trample◆◆◆ Large or smaller, foot, DC 25 basic Reflex
Source: Pathfinder Monster Core
Running this fight? Add the stegosaurus to the initiative tracker: type its name and the AC, hit points and Perception for initiative fill in, and the book button shows this stat block mid-fight.