[OOC] Return to the Rusty Rat

[DM Surranó]

To make it clear: Shanna has probably never sensed an aura of this strength in her life. Even if there's another aura it is surely suppressed by this overwhelming one. (see more in OOC thread)

The strongest she'd probably encountered is Universal Solvent but this thing is much stronger. Universal Solvent is CL20 (which is a joke, by the way). Technically, the term "overwhelming" in description of Detect Magic means CL21+, i.e. a true artifact.
She could not identify the school with 100% certainty either which suggests that her spellcraft roll (24) is smaller than the DC (15+CL/2), suggesting CL>=20.
Hint in spoiler tag.

Think about one extremely powerful Abjuration spell that may apply to the situation and apply some metamagic feat(s) on it to make effective spell level greater than 9.

I could give another hint, a much stronger one, if any of the characters would have the chance to actually realise that IC.
If any of you have any guesses what the item is, write me privately.
While I don't think the party (or any of the fey folk) could figure it out IC, players might still be able to guess right and I'm thrilled to see if some of you can, without ruining the "surprise" for everyone else. This is valid later on as well, as you will meet some clues which I won't emphasise but they will be there.