If they start declaring they're summoning gods of battle
About that....
In the Yoon-Suin setting there aren't a dozen gods in the pantheon. There are several hundreds. There are shrines and temples everywhere along the God river (which meanders all over the place). This means though that most gods don't have a lot of followers and are pretty weak.
The PC cleric worships the Tree of Memory (the player wanted the knowledge domain so I made up about half a dozen deities and she chose that one. A bit disappointed that she didn't choose Yato, Keeper of secrets, who demands the sacrifice of *hands*).
So when said cleric casts Spiritual Guardians, she doesn't summon spirits that serve the Tree of Memory. Instead, a ghostly version of THE GOD ITSELF shows up, and starts laying about with its branches, trashing foes left and right.
Now, will there be consequences to bringing forth her God in such a corrupt place? Well we'll see, won't we?![]()
If that's within her realm of doing that's one thing.
My example was more of "role playing in bad faith" that can often happen in RP when you remove the dice.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.