Another level or two certainly wouldn't hurt. Do you have your creature summoned? With a ranger or mage head it doesn't move around as much as with a warrior head, so even it it doesn't do much damage, it can be a distraction or act as a shield.
You may also want to get as close as possible and force Jagon to switch to a melee weapon, where he is not as strong (even if you are not as strong with melee you may do better than trading ranged attacks).
