As a warrior you can rush in and get close to him real easy his melee is weakish and you could finish him off quick.

And as Viru said if your a mage or ranger just hide between rocks and lure him out run side ways shoot quick and hide or let your pet tank him a bit whole shooting blasts and missles at him.

Even hide in the shadows works great to escape if you have a pet, you go invis but your pet doesn't, wich makes them go on your pet right away.

Don't play when you have a mushroom phobia! o.O xD