I know that some people going to hate me for this suggestion, but I think that is just right to be added to the game to make it a little bit more challenging. The idea is to add a penalty to the team that contains troops which are natural enemies to each other in the kind of same way as we get bonuses for similar troops in one team. Personally for me it doesn’t feels right that I can put DIvine and Daemon troops in the same deck and it goes smoothly together. Exactly in this case it could be more fun to add some penalty (we may call it conflict / morale / hatred whatever) like for example reduction of the mana surge chance for 5-10% for entire team. If we get more conflicting pairs into the team it will increase the level of conflict resulting an increase of penalties.
Let’s take an example. If we make team with human/human/divine/daemon it affects to conflict lvl 1. Human/divine/divine/daemon gives us two coflicting pair and results to conflict lvl 2. Divine/divine/divine/daemon is conflict lvl 3 and so on.
Opposite fractions might be: Divine-Daemon, Human-Monster, Dragon-Beast (dragons feed on beasts so it seems logical to me), Orc-Elf, Fey-Goblin, Knight-Mystic (mages don’t get along with warriors) etc.