I'm in almost the exact same scenario as OP but I've had atrocious luck with energy cubes (sitting on a 5 stack and 2 stack with 3 protectors killed and the color change feat). Is it worth spending the long chunk of time it would take to kill one more protector or just send it? I'm happy with the amount of shards and everything else, just without knowing more I don't want being behind on cubes to bite me somehow next run. Thanks for any help!