I have hit lvl 41 and Can't seem to find any more powers that I feel are worth a slot. I am Mercenary/Nature I have taken all the mercenary powers except slug. I have taken Regrowth, Life giving Spores, Wild Bastion, Rebirth, and Overgrowth in the nature set. My secondary power pools I have taken Flight - Hover, Fly, Group Fly, and Evasive Maneuvers. I took Leadership - Maneuvers, Assault, and Tactics. I am at a loss for what power sets are worth taking now, my basic strategy every combat is throw down Spores and have my pets target and kill something and rinse and repeat. I usually go few mob sets without even firing a shot myself.