Fight the Harder Version of the Final Boss
(To do this you must have seen the private action at Clik)
Save in front of the final boss and head back out the tower and go back to Central City and do a private action, then go into City Hall and you will see the same girl that was at Clik trying to warn the people about whats is going to happen. Now you can go fight the Boss.
the Final boss usualy has 500,000HP but now he has 1,500,000HP! most of his spells do 9999 damage which would kill you outright. all I have to say is good luck, you'll need it. ^_^