Not sure how to make it work. But was thinking along the lines of "x2ing" yourself wouldn't necessarily double your stats. It would really depend on the base percentages of your character. "Maxing" that percentage depends on the role you choose so it would remain balanced with other powersets. At times you could weaker than the tank. At times you could be almost as durable. Best example I can think of is a human Peace bringer before and after you click light form. It could be a toggle type power that increases your overall stats but drain endurance at a greater rate.
Just my thoughts
—
We're not here because we're free. We're here because we're not free.
I can see a Willpower set where such a thing could be the top tier power. You dig down, find the Inner Warrior or whatever, summon up ALL your reserves and go for it. Click ower that gives you two minutes of Uberness followed by a long cooldown, a big End drain and a panting animation...
I remember when Star Wars was cool...a long, long time ago...