Well, I don't know how to start so here are my suggestions:
1, Top Ten Players (or maybe Top 3) in the arena should be given monthly rewards and these rewards must be much much bigger than the ones that already given in tournament.
I think this will make the game more competitive and fairer for the one who have already at the top.
2, Now we only have Leaderboard for the arena.
I'd like to see Leaderboard for Strength (for The strongest hero of each player), Weapon (for the strongest weapon of each player), etc.
3, I think the game developers should create some special decorations that have ability to boost Heroes' strength.
What do you think of them?
Yes, I also think there should be decorations that boost the hero's strength /power/defense.