I love this game as is but I have some ideas that will improve the game:
- New trainner hero who allow increase special hability 100% for his color or 80% for a different color
- New battle item to decrease mana to monster.
- Increase the number of team from 5 to 6. As you have 6 flags in war you need setup 6 differents team. Depends each figth you change your heros but you can assing your best 30 heros to 6 different teams
- Battle item to change color of gems during a combat in order to perform better combos
- Include a new coin for get 4-5* hero or 5* hero
- New season where you can farm ascencion items to ascend 4* hero to max.
I hope that this helps you to increase the users experience,