Char #1 : the Ultimate KickZorxX
Nothing can beat him. Ever.
It is currently being fixed by Blizzard because this char is far too powerful, even with only signature spells. In fact, he doesn't need any signature spells at all.
See the Ultimate KickZorxX :
Char #2 : the Scare-Doctor
He scares monsters. Every monster I mean, including final bosses. And also NPCs.
It is currently being fixed by Blizzard because he also scares the players...
See the Scare-Doctor :