I think adding new nemesis to some faction is a good idea. There is at least 3 Nemesis to add that comes to my mind, 2 on the Beast faction, and 1 on the Eldritch faction.
The first beast nemesis would be based from the monster from Arkovian Foothill all the way to Asterkarn Valley. Here I think the best candidate would be a Manticore, or something like Troll or Dranghoul. If it is a Manticore, the design could be a nemesis with basic ranged attack and disengage rune skill. If the troll/dranghoul is the base type, then Iām imagine something slow and lumbering compared to Kuba, this type of Nemesis will be able to summon his allies, kinda like Mogdrogen fight. Either way, the damage type would be Bleeding and Acid.
The second beast nemesis would be based on Korvan Basin monster, perhaps makes them as half Undead half Beast. The monster type would be a fast moving mummies or beetle that is a host for a big maggot. The host is a melee monster with the damage type of piercing and vitality decay, once the host is dead the maggot nemesis spawn. The maggot is more of a caster type nemesis with leap rune skill and trap, kinda like Inquisitor rune or seals skill, the trap skill is also shared by the host. The damage type would be piercing and vitality decay, but the trap will also deal aether or chaos damage depending on trap.
The Eldricth nemesis would be based on the three witch god summons on the East Marsh temple, or even a non aligned eldritch creatures compared to Kaisan Korvaak aligned. This Nemesis could be a mythical Raven or an uncontrolled Wind Devil. They are a tank/caster type, but capable of using shadow strike and displacement rune skill. It deals Tri elemental damage and DoT as well, got no or low resistance shred, but has a high resistance in both elemental and physical resistance, or has native absorption either like inquisitor seals or maiven sphere.
If possible, these nemesis would only spawn in their respective area of the world, so Beast faction only spawn Kuba on the bog and jungle of Ugdenbog, instead of him getting plane ticket to the Homestead farmland. What do you think?