Dear Fido
You are a whimpering sack of congealing semen. You had one job. ONE. JOB. And you still managed to screw it up! Thanks to your blathering incompetence, Equestria was nearly thrown into turmoil by not-me! You're proof of the whole 'one head equals one brain, three heads equals piss-for-brains' phrase. Next time you decide to let a millennium old criminal escape his imprisonment in Hell, it best be me, you under-performing three headed lapdog mongrel.
Yours sincerely, Discord
P.S. Winona's pregnant, and Twilight says the pups are otherworldly. Applejack's just mortified; how you managed it without killing the poor thing is a mystery. Now everypony wants to get her a doggy-abortion lest she birth canine apocalypse, but Fluttershy is trying to save the pups; needless to say, there's been a lot of singing lately. I need popcorn for while this drama unfolds.
There should be a follow up letter like
P.S.S It turns out it wasn't your puppies... They were Spikes.
I would give you all of DragonPonies organs to write a 'Winona having Cerberus' pups' story.
4371471
Hm... I could really use those organs...
Yeah Cerberus, you had one job that you did perfectly for a thousand years, and then decided to take a day off. Disgraceful!
Discord, just because the animal can topple buildings doesn't mean it's big.
That p.s.
You had one job, soldier...
Tirek was freaky