Guild Wars description
Beast Mastery increases the damage dealt by your animal companion and its chance to inflict a critical hit. Many Ranger skills, especially those related to making your animal companion stronger, become more effective with higher Beast Mastery.
The Beast Mastery attribute increases the damage of a pet and enhances the effects of your Beast Mastery skills. The skill effects include disrupting enemy actions, providing your pet with defense, healing and other boosts and the ability to cause conditions on an enemy.
When a pet of a ranger dies, all of its owner's skills are disabled for between 10 and 3 seconds based on the owner's Beast Mastery level. If a pet dies soon after it is resurrected (approximately within 15 seconds), the owner's skills will not be disabled for this death.
As well as increasing the pet's chance for a critical hit, the Beast Mastery attribute will increase the pet's damage.
Beast Mastery will enhance these listed beast mastery skills.