Heres an idea, scrap the non functional 100 beast gauge and go back to 5 stacks with an indicator like monk's chakras or summoner's aetherflow. Make onslaught build 1 but have a 30 second cooldown, upheaval cost 1, fell cleave/innerbeast and their AOE equivalents cost 5, rework inner release completely or make it reduce the cost to 2 stacks for the 5 spenders, and put the damage down back on storms path while making it build only 1 again.