So here's a thought- a game where the BBEG is a bard who managed to fuck a demoness to gain power
There is one rule to character creation; every character must be a paladin. Every single character.
We had a bard villain who managed to outsmart a goddess by navigating through a trap realm she made, and became her lover. It was kind of cool because the goddess wasn't evil, just unaware that the bard was abusing the gifts she gave him, and the power he got from sticking his dick in her.
Make sure they all have perform, too.
That way they can face the bard in a rock-off as their hit band, the Crusaders, and smite him with their mad music-based flyting before smiting him the old-fashioned way.
BROTHERS! We must sieze a Fortress of Redoubt forthwith 'ere undertaking our noble quest, for the holy Imperial Guardsman's Uplifting Primer, which came to us in forgotten times of yore, explicitly states the advantageousness of a defensible headquarters from which to coordinate & support operations; I elect that one: [dubbles decides its name].