You should be about level 15 if you are a Hunter and have Resta, an Autogun, and Monofluids to restore your MP. When starting the fight, keep shooting at any part of his body. When he is up in the air and is about to land, get away from him or the rising floor will hurt you. His first attack on the ground should be an elemental breath attack. It consists of a fire breath (the weakest one), an ice breath which freezes you (the most dangerous as you can easily die while you are frozen), and a lightning breath which paralyzes you for a short while. When he does the breath attack, walk towards him until you are under his attack and shoot at one of his body parts. He should eventually take flight again. If he starts spinning in the air, then he is using his elemental ball attack. Like the breath, it consists of fire, ice (still the most dangerous), and lightning. During this time, try to evade as many as you can and heal if needed. After this, he will land again. Keep repeating the previous steps until he roars and goes underground. When he re-appears, there will be two of him. Fortunately, one of them is a mirage but it can still hurt you. You can tell if one is a mirage by killing it. When a mirage dies, you will see a bluish flash and it will disappear. The mirages also have a lot less HP. If you kill a mirage, the real one will be by itself again. Just keep attacking and evading as best as you can until it is dead.