Worries about Game design (King of Thieves)
I used to work on a mobile game with identical concept. It's called King of Thieves.
And it works better in all aspects, unfortunately. Let me explain.
In KoT you have stronger motivation to RAID dungeons, cause:
a) Your reward could vary in a very broad range. And you can see your potential reward in advance.
b) You actually STEALING form other players. So they losing some stuff depending on how successfully you rided their dungeons. It's a real pleasure - to make conceited dungeon owner suffer.
You have stonger motivation to BUILD a great dungeon, cause:
The only way to go up through the Leagues - is to expose part of you treasure (gems) for a while (1-8 hours). Gems are upgraded (merged) this way.
And here comes a great Trade off:
The higher value of the exposed gems - the higer will be an upgrade (merge) bonus. So, dungeon owner can choose a comfortable level of risk for his current dungeon. Play small if he's not confident in his defence and play Big if his defence is really ruthless.
There is also a great Balancing features:
You can REVENGE and get your tresures back if you raid offender's dungeon successefuly. And you can help your frends to return their stolen treasures (asynchronous).
That's altogether gives a really good social dynamics.
Also, they ended up adding a HEALTH mechanic, cause it makes everything feel smoother and easier to balance.
So, I highly suggest devs to play KoT and steal as much ideas as possible.
Here is the deconstruction of early KoT design: https://mobilefreetoplay.com/deconstructing-king-of-thieves/