I would like highlight a mechanic that is quite often used and permit some castles to be held at few to no cost, making it pretty irritating.
So here s the process:
Let’s say team A owns a castle. And for some reasons team A also have a hand on another team… B
Team A is bubbled and wants to to keep their castle while not having to do their cooldown…
At the best moment for them, team A will drop shield, and let the castle be conquered by team B… who then move his conquering prim from the castle, allowing team A to conquer it again.
Since these are just conquers… there s no cooldown… which makes the castle « easy to maintain » at no cost.
Basically, a way to by pass this would be to make a 24 hours windows…. And if a previous owner of the castle take possession of it again, he will have to do the usual cooldown for the castle tier.
This is not the most perfect solution, but at least it will break that abused mechanic, without breaking too much other mechanics.