I propose adding levels or perks to the alliance by beating titans, heroes in wars and monsters on the map.
-beat 10k monsters gives the alliance 1% att vs. blue heroes
-beat 1k blue heroes gives 1% def vs. red titans
-beat 100 yellow titans gives 1% mana generation
-beat 5k bosses on the map gives 1% special skill power
-win 100 wars gives 1% chance for rare titan/special quest/better loot.
You could cap it at 5% so its not a game changer but still fun thing to see the alliance grow.
It might also be interesting to add a vault where you can dump resources.
A couple of levels where the whole alliance receives 1 gem each day.
Not much but f2p will thank you.