Beastmaster's primary role is as an initiator with his ultimate, which is notable for its ability to pierce magic immunity, making it a great asset against heroes who rely on 
Black King Bar (or rage in the case of 
Lifestealer). 
Wild Axes at level 1 and I usually max Wild Axes then animals after your 
Call of the Wild Hawk vision range gets larger so the
greater Call of the Wild Hawk is worth it for that. in some situations I get 
Call of the Wild Boar at 3
instead. Your passive is not worth skipping obviously, but I am not
personally supportive of early levels of your passive. Sometimes you
might need to adapt to the situation though.