"For the last time, Luna." Celestia groaned through a double facehoof (+ wings), "We know that the floor isn't lava, thank you."
Luna grinned as she lit her horn.
"Yeah, but now the ceiling is lava!" she cackled, casting the spell.
Immediately, the room began to grow uncomfortably hot, and if it weren't for the sisters' alicorn nature, the two would've surely succumbed to the toxic fumes being generated as the tapestry and other various objects caught fire.
"LUNA!" Celestia hollered as the younger alicorn leapt through the window, "YOU'RE BANNED FROM VIDEO GAMES FOR THE NEXT THOUSAND YEARS!"
Luna poked her head through what remained of the rapidly melting window, making a face.
"Dear Faust..." Celestia complained as she cast a spell to undo the damage.