What other game modes would you like to see? Practice Mode Survival: Like a GW that keeps on going, and you can only use 2 squads. The power pogression would be from 75% to 120% you can cash out p...
I like the idea of a survival type mode like you describe above but I don't think you should lose all rewards. You should just keep the rewards you've received up to the level. Eventually you'll get to a level you can't beat.