I checked chapter 513 and saw your comment, Possibly me!

Princess Celestia stared at Nightmare Moon. Then at the moon. Or at least, at the void that filled the spot where the moon once was. It was hard to tell on account of the night being incredibly dark now without a giant ball of rock in the sky.

"So uh," Celestia held out a hoof to her sister. "Wanna call it a truce for now? I'll buy you a new Neighstation Too."

Nightmare Moon didn't say anything because the moon had been banished to her, grinding her into the ground. Unfortunately, Celestia did not see this as it was too dark to notice the humongous monolith of stone in front of her that was rapidly fragmenting the planet's crust as it began its descent toward the core.

"Well, I suppose this is better than banishing the sun to myself," Celestia mused as magma began to bubble up between the cracks.

and now the floor is lava.