Well, the first time he lands, he should charge. Then, when he comes to a stop, you need to throw something at him. If he stops charging, and tries to fight you, then throwing something worked, and all you should do is pummel him until he flys again. He will then land after a few flybys, and he will do something new, like swing his mace. Throw something at him and make him stop, again pummel him until he flys away. He will land again eventually and use a flamethrower, throw something at him AGAIN and he will stop to fight you again- pummel him once more. The 4th time he comes down to fight, he will charge until you throw something at him, then he will swing the mace until you throw something at him, then he will use the flamethrower until you throw something at him, THEN he will try to fight you and you should pummel him and kill him that time. Throwing things at him will not always work, it has to be big enough and an accurate hit.
Oh, and also, when he charges, you can't do anything. He has to come to a stop before you hit him with something. With the mace, he has to be swinging it when you hit him with something, and with the flamethrower, he has to be... flaming when you throw something at him.
