When Solar is fighting the alien invasion fleet towards the start of the series, instead of an XO suited troop, he runs into Genis-Vell, in the middle of his insane phase and wanting to help the aliens wipe out all life in the universe.
Solar is at the same power levels he was at in that story, and has the same experience. Can he win?
Make him go through enough energy or drain off enough, and he dissipates. The XO suited alien was doing ok, until Solars hand returned with a ton of solar energy and amped him up.
Genis-Vell was able to shunt Sentry's energy away, for one possible tactic..
^ I suppose it could work. Solar would still eventually reform, but it likely wouldn't be within a 'reasonable amount of time'... It's just really hard to judge. This early in the series Solar was still trying to hang onto his humanity, and had yet to utilize some of his more exotic/uber abilities.
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"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."