Honestly, I can’t see co-op being very feasible except for weird dungeon delves, and why would you do co-op and split up teams when you could instead have all 12 brothers fighting under one leader? AND co-op battles would feel slower. And having two bands of brothers on the world map wouldn’t be very intuitive, either. Would the game pause for each battle? Would you have a “turn” to spend? Would battles take “real-world” time? All of that sounds really clunky.
PvP “Me vs. You” custom battles could be fun, though. I set up my team, perhaps even with an option to play as the orcs or goblins or undead, and I duke it out against a friend. Fun, that.
The point of co-op would not be to split up teams but rather utilize 2 teams to battle larger foe’s. Each person would still control their own team and timers are always in play with multiplayer. If no turn is made in a set time then the AI makes the move. Either way it’s just an idea.
PvP weapons/builds becomes meta which requires a lot of balancing/updates/patching. I would rather see the devs work on in-game/pve content then have to balance multiplayer pvp constantly.