>>2287398I see what you mean about wanting to make the nudity a reward for success. If you're willing to sacrifice some of the more dynamic elements of the mechanic, you could make the event take place in a cutscene after you beat the boss of an area. In their dying breath they curse you, or something like that.
If you want to keep things more dynamic, you could try making losing clothes a sacrifice the heroine can make. Perhaps the justification could be a powerful ritual that places one of the clothing-lock glyphs in exchange for power, but either way you could give the heroine the ability to sacrifice a clothing slot for a temporary super-mode. Make the player need to collect items to be able to use the ritual and it becomes a reward for hard work while also naturally spacing out usages so people can't just spam it in level 1 and immediately walk around naked.