Controversial issues and their resolutions.

Here's the situation: you have wings, you need to build level 5 (or whatever the rules say...), you fly, everything is fine; and then the enemy takes your Castle with level 5, and... I'm sitting here wondering if I can still fly or not. It's interesting. On one hand, you built it, so you should be able to fly, but on the other hand, you don't have a Castle anymore.

To use scrolls and wings, you simply need to build the corresponding Guild, and that's it. You don't even need to visit the Castle with the built tower. Wings are like the "Flight" spell. You learned it, and even if your Castle is taken away later, the spell won't disappear from the spellbook, right?
Personally, I think this is perfectly fair regarding the building requirement for scrolls. Today, I played a game and found an explosion scroll guarded by 20-49 Gorgons, who were also guarding a can of food, a hut, and resources. It's scary to think how many there would be if they were only guarding one scroll. I personally found a Berserk scroll guarded by 20-49 simple Lizards. But building a Guild will be more difficult.