Lancelot

The main defense of the castle was in its ability to be submerged and hidden from sight, true, but the characteristic attribute of it was actually in its flexibility. Unlike most of the other castles I’d come across in my comparisons, Castle Avalon’s fortifications weren’t too far beyond ordinary — nothing like Lancelot’s Joyeuse Garde, which stripped intruders of their identities and forced them to fight a gauntlet of knights to regain the memory of their names — but it made up for it by making any fortification added part of the Noble Phantasm.