Scarlet Monastery: Cathedral Instance Guide
Scarlet Monastery is in Instance located in Tirisfal Glades. Scarlet Monastery, also known as SM has 4 wings. The Armory, Graveyard, Cathedral and Library. The Graveyard is the easiest where as Cathedral is the hardest. In order to enter the Cathedral and Armory you will need to grab the Scarlet Key which is located in a chest behind the final boss of SM Library.
The first boss you will encounter in SM Library is Houndmaster Loksey. This boss is technically optional, since he is out of the way and not required to be killed, but every group does him. He is also involved in the SM quest for great gear. To view the Horde SM quest click here. To view the Alliance SM quest click here.
SM Cathedral is the hardest of the Scarlet Monastery Instances. SM Cath also only has really "one" encounter with two bosses in it. It also has one optional boss, that drops a BoP green. The first boss you'll encounter, is the final boss, or bosses.
At the end of the Cathedral you'll find Scarlet Commander Mograine, standing in front of an Alter. He doesn't do anything unique during the fight, however it's very important that you clear all of the mobs in this room before engaging Mograine. If you don't when you engage him he will aggro everything else in the room.
When you kill him High Inquistor Whitemane will come out, and start attacking the group.
Once you lower her health to roughly 45% she will sleep everyone in the group and rez Scarlet Commander Mograine. Once he is up, you'll have to kill both of them at the same time. I recommend burning Mograine down first. Also, this time around Mograine will use his Divine Shield, since he is after all a paladin. Whitemane will just sit back and spam Smites on the group, as well as toss an occasional heal.
The optional boss can be found in the northeastern section of the Monastery. His name is High Inquisitor Fairbanks. He is hidden in a secret room that you must pull a torch-lever to enter. He is a very basic tank and spank fight.