Twilight cast the temperature regulation bubble over the castle and returned to her spell book.
After hours of neglecting the existence of anything else, the room became red enough to catch Twilight's attention. Her horn was also aching because of how much effort she put into maintaining the temperature regulation spell. "Curious," she thought, "I shouldn't be applying more energy to the spell . . . Not unless something is happening to it."
Ending her reign of laziness, Twilight finally got up and traversed bright scarlet halls to get to the balcony. It was there she discovered a scorched wasteland. Wildfires in the distance, the lake adjacent to the castle was boiling, Ponyville was lifeless. The sun loomed oppressively in the blood-red sky. With each passing moment, it was harder to keep the temperature protection activated. She now knew if she were to release the protection, she would surely die a heat death.
Twilight took the thermometer that Starlight left on the balcony and hovered it outside the bubble. It maxed out at 210 degrees before shattering in the extreme heat. It was much hotter.
It was too late to save anything. Laziness and her willful ignorance had destroyed Equestria. Twilight's inaction had doomed all life. Would it have been possible to save them all anyway? Would it have been possible to stop this? These were the thoughts going through one of the last living creatures on Equus.
More and more energy went into preserving the bubble, exponentially proving a difficult task. Not long passed until the sun became powerful enough to overpower Twilight. The bubble was destroyed and so was the Princess of Friendship, the last life.