First thing you need to do is run as fast as you can. just ignore all the monster in the first level.... walk over the bridge and a mini boss with mobs will pop up.... kill them all and proceed to the portal
after you reach the senond level.... dont run against the mob. kill them all.... for long range characters. you can use your long range skill over the monsters even when you are in the hills.... it will save you alot of time. and again kill the mini boss and proceed to the next portal where you can find the final boss
after completing the dungeon dont forget to open the chess
things you will get:
ordinary gems
incomplete stamp
keys
silvers
dungeon entry
and etc.