Well you can go many ways with new rules, but I gotta say first im welcoming all other additions in progress which are unique. I have some doubts about minions, only beacuse it can quickly turn into advantage for attacker (grimble, gobbler, skadi). If they make minions not count as minions, then it would be different story. Anyways here are some suggestions out of the blue :
There was already my suggestion about FRONT line rule in wars which would completely revolutionize approach and gameplay of it, making it more strategic and offer more approaches to handling it : WAR formations
But if you want simpler solutions like currently :
WARS :
catapults : defense down 15%
Mage towers : stealing 10% mana to 2 targers and giving to defenders
Graveyard : random chance for enemies to revive with 15% hp
TOURNAMENTS :
3 v 3 tourney
3 5* heroes vs 5 3* defense
4 4* heroes vs 5 3* defense
Healing effects are doubled in strenght & spell dmg is doubled