Well this is a tough one. I had started to pull out a few ideas but it seems that others are running with themes pretty close to what I had planned so mot sure what to do.

I need some inspiration.

Thinking an Hells domain cleric themed round 5s could be good fun to try. Hand of Law, Pentagrams, the Five rings of Binding, stygian mist (though I was thinking of a custom spell for each layer which would unwind this).

I guess to emphasise 5 I could narrow it to a Styx domain.

Hard choices!