Hogfather - Collapse

The boy clutched his head.

'I feel awful,' he said. 'Have you got any ice?'

Whereupon, because there are conventions stronger than mere physics, the building fell in.

The collapse of the Castle of Bones was stately and impressive and seemed to go on for a long time. Pillars fell in, the slabs of the roof slid down, the ice crackled and splintered. The air above the tumbling wreckage filled with a haze of snow and ice crystals.

Susan watched from the trees. The boy, who she'd leaned against a handy trunk, opened his eyes.

'That was amazing,' he managed.

'Why, you mean the way it's all turning bark into snow?'

'The way you just picked me up and ran.

'Oh, that.’

***

Hogfather - p139-140