Trouble is by no means an unexpected variable, especially today of all days. Leaders from multiple nations are gathered in Canterlot, specifically for discussing the balance of military influence.
With so many VIP's, its only natural for a wannabe conquerer to challenge such forces. As for one self-proclaiming overlord, 'Tainted Heart' seeks to unleash pure catastrophe. Sure his only experience is bullying small creatures, drowning his sister's favorite stuffed zebra, and graffiti, but that won't stop the primordial resurrection!
Though maybe he ought take change into account. People often experience trauma, so in time they're completely unrecognizable.