As of right now, you can continue ranking your clan up past level 10. But for 11, 12, and so on there are no additional perks.
With the style of perks given between 1-10, there really isn't much more you can do. So I would like to propose a new type of perk for extremely high level clans. These will be similar to the bonuses given in Boom Beach by Statues.
Create a perk rotation. My suggestion.
1. Gold Mine buff 5%
2. Elixir Collector buff 5%
3. DE Drill buff 5%
4. Barracks Troop Cooking Time reduced 5%
5. Dark Barraks Coooking Time reduced 5%
6. Spell Factory Brewing Time reduced 5%
7. Dark Spell Factory Brewing Time reduced 5%
8. Trap and Loaded Weapon Reset Cost Reduced 5%
9. Lab Research Time reduced 5%
10. Builder Time reduced 5%
Using all 10 of these could give clans perks up to level 20. And really, you could roll the perks set when you get level 20. These are minor changes and don't affect army or building strength, just time and resource gathering.
Implementing these some or all of these perks would help intice the higher level clans to continue a high level of play. And also reward them for success.
