Firstly, I think you could have posted in the help masterthread. Create topics for bigger things that can be talked about a lot...
Secondly, well, some bosses can't be beaten by power alone.
Some boss' spells are avoidable, try to avoid all the possible ones since Fradz is so weak.
Try to get EVERY possible item. Good items make a heck of a difference.
If you're just an average player, you should know that epic and elite bosses are kind of a little(a lot) more difficult than normal ones. If you want to kill them that badly, play in an easier difficulty OR keep trying, like, a lot of times.