A power that makes a wave of energy, the energy wave could be heat, solar-wind, or a few others, heat waves would travel at the speed of light, and cause planets nearby to heat up a huge amount until the wave has passed (This wave could be added in planet or star collisions as well!
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The solar wind/gravity wave would push planets and stars away slowly, and could be added to massive star collisions.
last power, extragalactic jets... Gamma or X-rays, basically, Black holes and Quasars (REEEEEEALLY big black holes) would emit a line of blue dust, this dust would look like long thin cones on either side of the black hole, and if they hit a star, may disrupt it causing it to premature eja... go super nova/hyper nova, and heat the crap out of planets.
Of course, to make it a power, You could be able to aim a gamma ray at something you don't like too much... =D
Note, I did not read other people's suggestions, (low amount of time), so if anything I said is similar to what others said, my apologies.