That's a big part of your problem right there. Big vases and some elites give you powers. Everything you kill and every object you break give you phasma which you can use to buy four more powers total from the two vendors. I walked up to the final boss with one that gave me an entire row of talents with their power doubled, 6k heal per attack, 6k more damage to each attack, -25% caster enemy speed, and a ton more. Almost 40 powers. Bugger hardly got a spell off. Though admittedly being a druid so I could just soak the curse, dispel it, and save my interrupt for bolts helped.