Legendary Lord: Malus Darkblade
In "The Jungles of the Gods"
near Caverns of Sotek there is a Breyherd "Khuguu Blood-Bringer"
I can't declare war on them and wipe them out, so I have a constant +3% Chaos Corruption every turn because I can't eliminate this beast herd. It's super annoying.
I've added a saved game as well as screenshot.