Record of Betrayer Muhark:
It's conceivable that the corruption of Muhark must have begun when he discovered the existence of Shak Dun Zu Hestui.
In order to fight Shak Dun, a known foe of Baium, Muhark only pursued physical strength. To him at that time, Rakan was just a defeated loser.
To obtain greater power, he went to the School of Giants and found an ancient machine that had been sealed.
The power that he obtained from that machine derived from the giants of the past. According to a dead soul of Atuba, Fatal Strike and Hammer Crush may be effective against his magic.