Q274 Looking at relic items, it states:
Now it never specifically states that the spell slot has to come from the divine spell casting class. Additionally the metamagic feat Alternative Source spell allows you to prepare arcane spells as divine or divine spells as arcane. So could you first prepare arcane spell slots as divine with alternative sourced spell, then prepare divine spell slots from your divine class, and finally sacrifice a normally arcane (now divine) spell slot to power the relic instead of a divine slot from the divine class?
I'd say just UMD it and skip the whole mess. If you can UMD away expending a turn undead use, you can UMD away expending a spell.
Hmm, I know you can emulate having the class ability, but I did not know it gave you an effective use of the ability to activate an item. For instance, I can see emulating the ability to cast divine spells to activate a karma bead. You dont need to expend any spell slots, just have the class ability. But I am not sure you can activate a Bow of Songs which requires you to expend one of your daily uses of bardic Music. Is there an example somewhere where you can use UMD to emulate expending a turning dead use per day?
Now for my use, you could probably use UMD as you suggested followed by the expenditure of an arcane spell slot. I have alternative sourced spell anyway for divine metamagic, and it says while preparing your divine spells you expend the slot, so I threw that in for completeness.
Relic are extremely powerful at reducing item costs if you need the extra capital. I have a build with dead end caster class progression and slots that go unused. Might as well put them to use.
Bard 1/Cleric 1/Wizard 3/ Dweomerkeeper 2/Eldrich master 4/ Sublime Chord 1/ Dweomerkeeper 12