Saga of Jaraah
The Beastmaster is as described in the Complete Ranger’s Handbook with the following adjustment:
Animal henchmen gain extra hit points and attack bonuses the longer they stay with their Beastmaster. After joining their Beastmaster, animal henchmen gain +3 HP and +1 to attack for every two levels the Beastmaster gains after the animal henchman joins the Beastmaster.
For example, if Belle, animal henchman, joined Urgoff, Beastmaster, when he was level 4, then Belle will gain +1 to attack and +3 HP when Urgoff reaches level 6 (2 levels gained since Belle joined him).