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Create a custom rule that adds Regenerator to the entire team. A perhaps simple but fun and interesting implementation. Same thing with Protean (I think there was already a protean metagame, a custom rule on it would be nice too).
Rejecting this on the basis that there's very little point, plus it would be a waste of dev time for something so niche - just ask your opponent to agree to the rule.
Have a nice day!