Twilight Sparkle: My idea is a Failsafe spell.
DM: This rings a bell.
Twilight Sparkle: Not just Dispel Magic, but a reversion to a predetermined set of properties to all entities and objects in a large area.
Applejack: A reset button for all of Ponyville? That's… ambitious.
DM: You're… talking about a power of a god.
Twilight Sparkle: Or a sufficiently prepared wizard! I proposed this to you privately a while back. During our adventures, if I placed focuses all around Ponyville, attuning them all to the same specific point in time…
DM: That idea?
Twilight Sparkle: Yeah! You said the theory was sound!
DM: Did you actually inform me that you were doing that? And that you were spending the appropriate resources? Did I confirm it?
Twilight Sparkle: Well I mean– I was hoping… we could say, in the past…
DM: Ugh, we went over this last time! No more retcons! No more setting things up outside the session without consulting me first!
Twilight Sparkle: Sorry…
DM: This isn't a heist movie! You can't just get out of trouble via flashback!