The easiest way to kill this boss is to first clear both rooms of mobs. Then one in your party start the quest while the rest is inside one of the rooms. At the time you start the quest, run as fast as posseble inside the room where your party is.
When you are inside, the tank should get ready to taunt the boss, since it will run after you. When the warrior got agro, DPS him as much as posseble. When you see him cast a portal, the whole group must run into the other room very fast. If you do this, the boss will follow and the portal will not summon any hard elite mob. If you do not change room, you will have to face Arcubus, level 68 elite mob. He hits very hard and you will most likely whipe if he shows up.
At low health he will change form and hit much harder. But it should not be any problem at all if you keep DPSing, because he will die soon after he changes form. After he dies, loot the key and run back to the dragon. Release him and you will fly away with him to the dragon from the sky and Mordenai. He will reward you with one of the following items:
http://www.wowhead.com/?item=31493
http://www.wowhead.com/?item=31494
http://www.wowhead.com/?item=31490
http://www.wowhead.com/?item=31491
http://www.wowhead.com/?item=31492
To sum this up:
1. Clear the rooms
2. Group gather in one of the room and one of you start the quest.
3. Run inside the room your mates are in
4. Tank get agro
5. DPS him as much as posseble.
6. When he casts portal - Change room quickly!
7. Watch out when he is low hp. Changes form and doing heavy damage.
8. Kill him, loot the key and fly away with the dragon and get your reward!
TheWoWDB
