Not all domains that provide magical power use spells, but for those that do, these are the rules.

Spells come on Domain cards, just like any other Domain ability. They need to be simple enough for their entire description to fit on a card.

Spells are tagged so they can be classified.

One special set of tags is [Arcane | Divine | Nature]. All spells must have one of these tags, which specify the source of the magic.

Other tags exist for various reasons which are used to clarify the spell's role, who can use it, etc.