[saulrh]

Maybe have the investigator player redo the fight with tweaks.

Now that I've had some hours to think, this'd actually work better in a single-player format: The player can only advance by tweaking enemies until they can defeat them, knowing that the next time they encounter that enemy it'll be stronger in exactly the wrong way. Then it becomes a complex game of managing how the enemies grow and balancing tactical concerns ("how do I beat this one enemy") versus strategic concerns ("I could beat this one by decrementing its dex, but then it'd be unstoppable in the future.").

EDIT: this feels a little bit like "warning forever" but maybe with more depth and a clearer focus?