How about the idea. if a person is online during a war attack, or watching an attack on their base they could maybe drop a spell to rage their Heroes or CC. Also if they have a Hero they could use their ability to help protect their base. If this case the defender would have to have the spells trained before the attack started. Heal, poison, rage, freeze, lightning, could all come into play. I think if this was a feature in war having the ability to know if a person is online would be good. That way you can stall attacks and add a new dimension to the game. Maybe waiting to the end of the war isn't the best time to attack since everyone might be online.
What do you think?

