Larian Studios Forums Divinity - Original Sin Divinity Original Sin - Help/Tips/Tricks Prison in Faery realm- how to progress?

I've just got into prison where White Witch is supposed to be kept (Imp told me how to get there). But every time I try to leave room with Iron Maiden, I get killed with lava by Sentinels who shout "intruder detected". Am I supposed to look for some other way?

EDIT: "My" solution: Rogue with Cloak and Dagger skill teleports to the middle of chamber, waits until cooldown ends, teleport again. If he doesn't move after teleportation, sentinels won't notice.