Pony Of Mass Destruction-Short version, do not piss off an alicorn.  Don’t make them angry enough that they want to break out the entire toybox of means they can deal with threats.  The weakest and youngest of all alicorns, Prince Lucifer Morningstar, once picked off battleships from the surface of the planet he was on.  Without a magical amplifier, killing each ship with single shots.  He was tired when he was done, but that was about eight battleships later.

What one of the older alicorns could do almost beggars the imagination.  In theory, Princess Celestia could turn Equestria’s sun into a Lensman-scale sunbeam.  Princess Luna could drive you mad in your nightmares that would never end, even if you were wide awake.  Princess Cadence, the weakest of the four eldest ponies, could destroy every feeling of love and loyalty you ever had (and this is a state secret so high even other alicorns don’t know about this).  And, Princess Twilight Sparkle?  She’s the head of the Ministry of Magic, one of the three ponies in charge of the Ministry of Ghosts, and has access to all the toys.

(Also, they have control, as much as sheer power.  Any “Fall of Equestra”-type situation would end in this universe by the simple fact that Celestia could and would teleport instantly a pinprick sized piece of stellar plasma into the heads of every invading Caribou.  Tiny pin-prick sized piece, just enough to reduce their heads to an instant cloud of floating red mist…)