Tank
Use a ranged pull if available to engage only one of the drakes at a time.
Pull the boss into the hallway, and tank the boss up against a wall facing away from the group to minimize the effects of the boss' knockback ability and keep your other party members out of harms way.
Damage Dealers
Both Melee and Ranged DPS players should stand away from the front of the boss to avoid it's frontal cone attacks. Otherwise, just make sure the tank has threat and maximize your DPS output.
Healers
While healing, stay away from the front of the drake and focus your healing on the Tank, as other party members should not be taking damage.