Build your castle with a two-layer design, and make sure there's just one entrance point to control the flow of raiders. Place graves right behind the main door for banshee spawns, and don't forget wooden windows on both sides to attack siege golems safely. Honeycomb your room layout to waste raider resources, and maybe add some visible stairs as a decoy target.

Set up vermin nests in the second layer to unleash plague rats, and position your best servants (90%+ blood quality) with top-tier gear around the castle heart. The key is creating buffer zones with extended walls to slow down approaches, while your banshees and rats keep raiders busy dealing with constant harassment.

During active raids, use those wooden windows to chip away at siege golems, force attackers to deal with your summons, and make them waste time clearing through multiple layers of defense. Your servants should be spread out strategically, some guarding entry points, others hiding in honeycomb chambers ready to ambush, and the strongest ones protecting the heart directly. Time wasters and decoy rooms at the edges of your layout will drain their siege resources before they even reach anything important.