There are a few castle never exploits you can do. The first being fighting the 2nd boss tal'gath the watcher there is a vase right before the cut scene on the left. You can get on top of this vase using a crack on the left wall. Climb up the crack and then jump to the vase. Last thing you need to do is have one person agro the boss and pull him over and done. There a skip to the third boss xivros.
Right after defeating the green jelly on the right side railing you can jump on then jump across to the platform. Then you can use the vase to get across to the portal. You can then go where two red wizard are located and jump to them.. On the right there is a large rock formation you can jump in between and walk along the left side where you can use the wall to jump to the top of the column.
Lastly and big glitch is you can use an HR and GWF. Everyone goes in to fight Draco the party wipes but the gwf will stand at the door/pillar when a wright hits him it will push him to the top of the wall also been told can use mighty leap but haven't seen this way. This will lure Draco to the gate and the gwf won't get hurt then on. The HR turns around back facing to the pillar and use maruader's escape and climbs to the op of the hate where he can kill Draco without getting attacked.