There is a bug with Beta Ray Bills Green power when characters are 'away'.
I had sent 2 enemy characters Away via Kangs Blue and only a single character remained in the battle. I tried to use BRB's Green power and it said 'no valid targets'. Apparently if one of the targets selected at Random is away you can't fire the power even though there are other valid targets available to select.
It may be that you need to take another turn for his Green power to realize the 'away' players are not valid targets because in another battle I was able to fire it on a later turns when characters were already away.
KGB
@KGB FYI that Devpool took note of this: https://www.reddit.com/r/MarvelPuzzleQuest/comments/12c2bom/devs_can_i_report_a_glitch_here/jf0dckz/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=1&utm_term=1&context=3
This has been fixed and going up with tonight's patch!