Heroes 5.5 WarGame Edition - Tactical Edition.

Yes, I also have doubts about the technical implementation. But even with such an implementation, the racial bonus won't work in the early game, since you need to build a structure to choose sworn enemies, and it takes quite a while to build that structure. That's what's frustrating – an entire base and a perk that don't work for a long time. The motivation to change sworn enemies could be "strengthening" the army through special perks. As far as I remember, you have implemented such perks – summoning Manticores, for example. In The Restoration of Erathia, Necromancers get Death Knights. In the end, if I know that the opponent will have a достаточно dangerous stack of high-tier units, then the motivation to find it on the map and set it as a sworn enemy is quite significant.