I've done a shaman NPC with some true believer powers and sponsored magic with a snake theme for Cradle of Darkness. The mix works remarkably well. I'll see if I can find the writeup again.
EDIT:
Found it.
Bless this House
Guide my Hand
Righteousness
Holy Touch
Sponsored Magic (Coatlicue)
So yeah, basically a full true believer plus sponsored magic, as it seemed fitting for the type of goddess I had in mind. I had originally thought to put some shapeshifting in the mix but decided against it.