I laughed so hard at this. Keep it as an easter egg. This bug report is just because, well, ultimately this is a bug, and maybe someone can reproduce it and have a giggle.
Platform, device version and operating system:
Android
Screenshot or image:
I so wish I took a video of this. 
What you were expecting to happen, and what actually happened:
I confused the game and it broke hard.
Wild Plains couldn’t progress in power until my shaman reached level 80.
I started a GAP, doing explore at Wild Plains while using shaman and Tink Steamwhistle (this is relevant later). Finished a battle and shaman levelled up to 80. The game should have gone back to the explore menu but first it gave me the animation of the kingdom power increasing, then went back to the explore menu.
Commence game confusion. My UI started to fall apart.
For every battle after, i had to double tap my troops to display their spell instead of the regular single tap. Weird.
Once GAP ended, I went to my inventory to take note of my rewards. Scrolling didnt work quite right. Normally, you can flick and it scrolls a fair amount, and you get a white box briefly around whatever you initially tapped. Here is a boring video of that which shows it better than I can explain:
But this isn’t what happened. That white box would never disappear. It stayed during scrolling, even after I stopped touching the screen and after scrolling ended. The white box would move if I tapped other things though. Also the scrolling animation was clunky.
Then, I went back to the world map. I tapped the Games button but it didn’t open. Instead, the Troops button highlighted. Tapped Games a couple more times, and each time Troops would highlight.
Ok, so I tapped Troops. IT TRIGGERED THE SOUND EFFECT OF TINK STEAMWHISTLE DYING. 
I dont know how, but omg, the sound of death…
Well, after that, everything worked again. RIP Tink.
How often does this happen? When did it begin happening?
First time it has ever happened.
Steps to make it happen again
I am guessing that this is what broke the game:
-have a kingdom unable to progress further in power due to a class not high enough in level
-level up that class to the power requirement while running explore in that kingdom
-witness all the breaking
