Dragonlance and Ravenloft
The whole of Krynn and its cosmology is a single Domain, of which Takhisis is the Darklord. The whole balance/cycle thing is her curse from the Dark Powers - evil is doomed to arise again and again to seek domination, but always to turn in on itself and fail. Kender are of course an aspect of the curse. The smallest, most innocent people in the entire world - and the Queen of Terror can't frighten them. It must drive her nuts, like a stone in your shoe you can't quite find and get rid of. Fizban appears as he does because Bahamut really IS a well-meaning bumbling senile fool, but every time Takhisis has him on the ropes some stupid coincidence or bit of bad luck or unlikely fluke means her plans fall apart.
Edit: and it explains the Cataclysm too. This was possibly the closest Takhisis has ever gotten to winning. She subverted the greatest empire of good that the world had ever known and turned it to evil (even though it was unaware of that fact). And then the other gods threw a mountain at Istar and wiped the whole thing out. But would a good god do that? Hell no. But a Ravenloft approximation of a good god, a puppet of the Dark Powers who only exists to torment the Darklord, certainly might. Extremism in good turning to evil is very Ravenloft, and wildly over-the-top retribution against disappointing minions is something Takhisis would understand. The good gods of Ravenlance aren't actual good gods, they're Takhisis's idea of how good gods would behave...