Today i decided to pay a visit to the Patriarch's Lair and upon reaching the area where theres alot of dragonheads shooting fireballs all over i see on the map a section blocked off by a wall. after 20 mins trying to figure out how to reach that area i decided to give up and continue on with the place.

Also just before reaching the Patriarch i fell upon a key but i didnt find any locked chest or locked door so im kind of wondering what purpose that key serves ... anyone got infos that could help me?