Red Flags: Necerion, Faerie Fire, and Disappearance

[Byron Zibeck]

One question I had while preparing to run Part 6. A key part of Necerion's tactics is that he casts Disappearance to gain invisibility as he follows the PCs to the vault. But the adventure states that anyone casting magic within the Citadel is struck with a 24-hour Faerie Fire, which reduces all forms of invisibility to concealed. So wouldn't the PCs be able to detect him then?

Am I missing something (like the Faerie Fire does not extend to the inner portion of the citadel) or does Disappearance somehow trump Faerie Fire?

[Edge93]

The module mentions that the Faerie Fire ward does not extend past the door to Whark's Nest, correct. Good question though.