How to solve castling effect?

[Norfleet]

Originally posted by Taqwus:
Then garrisoning all those bloody castles is expensive unless they're undead, most of which defend the gates rather poorly.

The castles AREN'T garrisoned: Usually, they're instead defended by mobile forces that teleport, gateway, or fly between the threatened castles. The drawback is that in order to make this in any way affordable, the castles tend to be constructed of paper and breach quickly, necessitating a rapid response: Attacking more castles than your opponent can respond to at once will pose major problems for him.