What is the fastest possible way to level up you’re castle to 11??
The fastest way to level up your castle is by completing the recommended quests. These usually help out by showing you what to upgrade before you can level up your castle or unlock cretain things.
Simply click go and upgrade your buildings or go and complete researches.
You can speed the upgrades up using speedups. These can be gotten from hero stages, monster drops or other prizes. By joining a guild you can save up guild coins to buy speed ups too.
Hope that helps