which thief ring there are two
there is a passage it starts (ends) where u battle the last slaver - that2 one with the ranged weapon - forgot his name (in fact i never know him) and end starts where the door to slaves is
one ring is at the first (second) mushroom place where the coins are
the second ring is together with a skull in the small pond u came across
it's in a corner at the steps/ridge i think u must use a night eye spell or manipulate the gamma to see him!