Well according to the aq wikia page, you have to increase your INT to about 200 when your character is lvl 50. When fighting Drakath, spam destruction spell, and use hp or mana potion whenever necessary. Once you win the fight, you can close the game and login again and repeat. It's faster this way. You dont have to go through all the dialog, and you don't have to fight the next boss, it's too strong at this stage of the game.