Welcome to the Hydlaa forums.
Somehow I believe you should ask this question in game...

Anyway, a few hard to beat opponents are: Ulbernaut, Maulbernaut; a few wild Tefusang (or was that a bug?), Marfusang; Dlayo Gladiators; Cutthroats; Onyx Dagger rogues ...
It's up to you now to rate them for an order.