South part of the sewers? Just throw one of your tellies over the SOUTH gate, teleport yourself in - or use telekinesis for the chests, but you won't get the barrel then. There's a lizard mage in there.
: How high is your spiritual resistance? Over 15 is safe: Polymorph bug when opening one chest: Croakcroak.
Don't tell I didn't warn you
... there's another one in these sewers: Bunny danger.