Imperius Rex is an ability.
This ability grants Special Attacks to deal up to X% additional damage based upon stacks of Outrage. The ability also guarantees that Special Attacks cost X% less Power.
However, while Imperius Rex is active, the Champion drains X% of a bar of Power each second, and an additional X% of a bar of Power every time a Special Attack is launched. Lastly, while Imperius Rex is active, the Champion may not gain Power from any sources other than their own abilities.