Which class’s ultimate ability do you like the most?

I actually like the super ability of the forest elves and dwarves! The elves' avenger is "Super" if you know how to use it properly!!! And the rune magic of the dwarves really helps them!!!

Actually, avenger and rune magic are not special abilities (SA). The SAs of elves and dwarves are constant luck and constant bad luck for the opponent, respectively. And both of them are really very good.