Yeah you're right, it's there, and ONLY there.
I noticed that all the FAQs were wrong, so I made my own list of where all the cloaks are.
I'll post it here for your reference, and rest assured this is where I found ALL the cloaks, so they're DEFINITELY in these places.
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Faery Cloak (Faery Realm):
Absorb Boobrie's Id, then break the stone of thought you can only break with him for the cloak.
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Battlefield Cloak (Warcadia):
Complete the quest which has you escorting a Bullseye. The cloak is the reward.
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Cloak of the Deep (Undersea City):
When you have absorbed at least one of each of the folks in this realm, a lightning element stone of thought appears in the first room of the Forgotten Palace area. It contains the cloak.
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Cloak of Dawn (Endless Corridor):
There is a Habletrot which you must defeat within a time limit. Beat it within the time limit twice for the Cloak as a prize.
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Cloak of Twilight (Hell Realm):
You need to break 5 stones of thought in Hellrealm, then break the 6th stone south of the Final Portal. If the 6th Stone is not there, you had missed one somewhere...
Location of the stones of thought (from the portal in that area):
1. Hill of Brimstone 1, North, Nort West, Coblynau, Mandragora
2. Hill of Brimstone 1, North, North East, Boggart, Fachan
3. Condemnation Tower, Level 2, East, Wryneck, Beithir
4. Condemnation Tower, Level 3, West, Ulbyr, Ulghter
5. Hill of Brimstone 2, S, Caesg
6. Inquistion Bridge, South, Baolwind, Baogbolc
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Cloak of the Midnight Sun (Chapter 7):
This cloak is gained automatically at the start of Chapter 7.