Sacrifice only has one meaning.
The students and the professor who heard this fell into thought for a moment, trying to figure out if what Klaus meant was something literal or figurative.
Headmaster Earl Ludwig took a step forward. "What do you mean by sacrifice. Even if it's a joke, there is a limit to it, Klaus." Headmaster Earl said in a serious manner.
At the same time, he whispered through each professor's ears through magic. All the professors who heard his command readied their bodies and spirit.
"Make haste. Once they're distracted, take the children and look for a place to hide. We cannot escape the veil. Our only hope is to wait for assistance. Those instructors who have high attack magic must stay with me."
"Joke?" Klaus grinned. He brushed his hood off his head; his expression had turned disgustingly happy as if he were a child about to open presents. "Have I ever uttered a joke in all my classes?"
