Vulcan has four stages depending on the state of his HP. The first is at full health, where nothing out of the ordinar will happen.
At 770000 health, a pool will spawn on the ground. It will grant you one of two buffs: Wasteland, which increases your critical strike chance by 50% and also reduces your skill cooldowns by half, and deathrattle, which increases all your damage by 20%.
At half health, he will begin to pull every member of the party under him while shouting, "Us? Failures? You must be talking about yourselves!". Almost immediately afterwards he will do a large AOE under him, so it is imperative that you run away from him immediately. He will continue using this attack for the last stage as well.
At 330000 health, the orbs will spawn. They are untargetable, will let off a potent AOE every few seconds, and will aggro onto someone in your party. Spread out over the field, and quickly identify who has the aggro on the orbs. Have that one person lead the orbs AWAY from the boss and other players. In this stage he will still use the grab and buff pools will randomly spawn. After a while, the orbs will disappear and respawn, so you'll have to identify the aggroer again and lead the orbs away again.
Do note if somone leads the orbs onto the boss and the boss executes its pull ability, your party can get wiped relatively quickly.