Cheesy tip,
Just summon 5 creatures and throw them into the room spike room...
Meanwhile, make sure your party is in the room with the long table out of sight and drinking tea and generally making merry.
... if a summon dies, summon another and replace the slained in battle, for some irrational reason by the way, summons do not trigger the traps in the 'Spike Room'.
If you run out of summons and summoning spells, just rest and then proceed to summon more!
Of course you could join them in the fray, but due to the annoying risk of being level-drained and the fact that you may have an spike stuck up you a**, letting your gee-they-are-immuned-to-traps-summons do the dirty work or you seems more preferable.
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If not a Sorcerer, then a Paladin.
