This calculation attempts to measure the size of the hole in the castle ceiling that Sphinx would need to vaporize, to bring Bordeaux and Libre, who were upstairs from her, down to the floor below, while they were fighting each other.
It will take into account the fighting distance between two combatants who are fighting with poleaxe/double-bladed sword.
The fighting distance will result in the required size of the hole.
Re:Zero EX Volume 2: A Song of the Sword Demon
http://rezero.wikia.com/wiki/Wilhelm_van_Astrea/Synopsis
She tried to vaporize them with Al Jiwald, yet her plans were foiled when Grimm blocked her magic with a shield, resulting in the heat rays being reflected up to the ceiling, vaporizing it to send Bordeaux and Libre down to their floor.
Bordeaux vs Libre fighting with their weapons
Low-end
The combatants are wielding polearms, so I will assume 1.5 meters for the minimum fighting distance between them. This is the radius (r). It would become a 3-meter wide hole.
The minimum ceiling thickness (h) of a common house (12-14 inches) is 0.305 m or 12 inches. The battlefield here is a large castle.
Ceiling hole cylindrical volume (π*r*2*h): 2,160,000 cc
Vaporization energy: 25,700 J/cc
25700 J/cc * 2160000 cc = 55,512,000,000 joules = 13.27 tons TNT or City Block level
High-end
The smallest Kendo court is 9 meters per side, or 4.5 meters of maneuvering space for each combatant.
l*w*h* = 9 m * 9 m * 0.305 m = 24,705,000 cc
25,700 J/cc * 24,705,000 cc = 634,918,500,000 joules = 151.74916348 tons TNT or Multi-City Block level