[@Rai]

Was thinking in a spell to help the GM to preserve things. Be they cities, *ahem* trees *ahem* :lol & etc. But at the same time, allow the satisfaction of destroying everything.

A spell with a lengthy casting time. Conjures a big magical circle affecting said area. All the things (maybe people too?) inside it will create an exact copy, a "reflection" under this magic circle, almost like a mirror. Upon the completion of the spell, the reflection and the real things will change places. The "reflections" can be completely destroyed, but as long as the real thing under the mirror is ok, when the spell is lifted, it will change places with the reflection again, completely unharmed.

It would be something exclusively lore-wise. Too lengthy and requiring a big source of power (other mages to help the caster.)

Edit: Maybe a spell exclusive to Mirror?  (Hence the name? :lol)