[SquareKnot]

Right, it's the whole "caster of one kind trying to pretend to be another" theme that I'm interested in. That's what inspired the question.

And as to some spells making it obvious what the caster type is, first that would assume some extensive knowledge of the magical type. Does a typical farmer know that Fireball is only an arcane spell? Probably not. To a commoner, it would make some sense for a priest of Pyrtechon to have that ability. But a wizard might know that it's an arcane ability, or a cleric might know that no priest he'd ever seen could cast a fireball. Which was the other part of my question about casters of one type knowing whether a spell was one type or another. So how to play that knowledge? I was thinking that if a character started to get curious, a dicebag roll might persuade the player to reveal whether the spell was a certain type or not. It would have to be worked out in tells between the players, most likely.

Many spells cross various caster classes, but many are unique to a given class.
casting Mage Armor, Shield, Fireball are obviously arcane,
while healing spells or trying to turn undead easily mark a clerical type.

Except a bard can cast Cure Light Wounds as an arcane spell, and a cleric of Lucinda with Magic domain can cast Mage Armor :)

On a GM-led quest, pretty much anyone with half a point of Spellcraft can tell the difference between arcane and divine magic. All magic on Layonara comes from the Weave. Arcane casters channel it directly, divine casters have it "filtered" through their respecive deities (or "nature" for druids/rangers).

Drat. That's what I was afraid of. I was trying to pass off divine for arcane to someone who was a cleric and a wizard. Guess that probably wouldn't work.

Thanks everyone.