Leaving Stormcaller Brundir last is the normal fight for the Iron Council encounter. Brundir starts out with Chain Lightning, which can be interrupted, and Overload, which can not be interrupted. It's a good idea to send one of the healers to the back with the tank on Brundir. Make sure the healer is aware of his Overload ability and moves accordingly. After the first boss is killed, he will begin using Lightning Whirl. This is also interruptable and should always be as it causes a lot of damage. When Brundir is left, he will also cast Lightning Tendrils. During this he will lift into the air and shoot lightning to the ground. It might be a good idea to have the entire raid run towards one side of the room, while the target of the tendrils runs towards the opposite side. This will avoid a lot of party damage, but be sure that person doesn't run out of healer range!