With the bodyguard run of monsters coming to an end a couple of ideas for what could come next.
Nemesis pets/bodyguards-pets could be strong against their own element and bodyguards strong against their weakness. (xirons pet has access to nature attacks, xirons bodyguard has access to fire attacks)
Another idea is unique monsters for each general.
Atums battlerager. Based on thibbledorf pwent from the forgotten realms.