How about fast lords?
The kind that send the low level people running for cover as fast as they can?
There is nothing scary in this game for monsters, in a map, you can always stand back if you have to, a lord you can always run away from, rexes are slow too.
We need some insane-hard-to-fight-lords
Secondary note:
New lords should use better tactics too. If a target spell is coming at it, it should go around an object like a tree. And whatever this lord is, it should be able to use ranged attacks in attack and retreat style fighting to those stronger, and jump/dominate with melee those that are weaker.
It would encourage people of different levels to play together too, you always need bait