Bolster Companion (Ex)
Source: Advanced Player's Guide, p. 128
The ranger can use this trick as an immediate action when his animal companion is hit with an attack or a combat maneuver. The companion’s AC and combat maneuver defense increase by +4 for the purposes of that attack. If the attack still hits, the animal companion only takes half damage (if any). The animal companion must be able to see and hear the ranger to benefit from this trick.