Automated towers that fire mercilessly into the rising enemy army and go inert once the throne room is entered.
The plan accepted the towers as an unavoidable hazard. The remaining defensive towers would be firing during the storming of The Castle, and there was not much anyone could do about it, but the moment anyone set foot in the Throne Room, all the towers would go inert.
In the meantime they worked for the crawlers too, firing mercilessly into the thousands of frozen enemies drawn up out of Larracos and along the side of The Nest as they drifted toward Princess Donut's Astral Paw.
Defensive towers positioned around the city, continuously firing into the ascending mass of frozen enemy soldiers.
Automated defenses that shred the rising enemy army but also threaten the allied castle assault.