Just spent the last 4 hours killing Huuptics and Evol Ews and still no tattered robe :( I only got chest drops from the huuptics like 4 times and I spent like 3 hours on them. The last hour I spent killing evol ews and all that gave me was a single thulian puzzle box. Btw, if you are soloing the lizardmen and they are white or blue to you I highly suggest mezzing or stifleing or stunning the evol ew mender in the mobs because he is the most difficult healer. Personally I used my only root spell on it which also stifles, made a great difference.
Unexpected drop from Evol Ew lizardmen near the camp just to the right of the zone in after you come through the tunnel. Dropped from the trio of disciple, mender and warder.
