Nuclear payload strapped into the back half of the Reaver castle's largest sentry dogs.
When the first lion-sized sentry dog leapt into the entrance hall of The Reaver Castle, a massive glowing bomb notification hung over its back half. Elle froze the creature into a skidding block of ice and Carl rushed forward, lifting the burning-cold block and pulling it into Carl's Inventory before it could detonate. He read the bomb label without a full Examine: Mini Tactical Nuke.
More of the huge dogs followed. Donut evaporated one with Magic Missile without setting the warhead off. When Carl triggered the No Disassemble EMP Bombs inside the structure, the EMP pulse fried the dogs but did nothing to the warheads, and at least one, maybe two, went off, blowing The Reaver Castle apart from the inside and hurling the crawlers away burning and spinning. Carl's only thought as he tumbled was that these bombs were much smaller than he had feared.
A payload occupying the entire back half of a lion-sized robot dog, announced by a massive glowing bomb notification hovering over it.
The Reavers' doomsday security measure, which ultimately destroys their own castle.