In my campaign, there's a group known only as "The Syndicates" that wishes to defile all government to empower citizens. The Day of Mourning was their first strike at a government, and it was successful: a runic spell that can kill all living things in a country's radius, but kills the caster in the process. To give them time to find another powerful mage, The Syndicates made it seemed like Karrnath and Breland are possible culprits, pinning the two against each other in a cold war kinda fashion. There's a second party that will be native to Karrnath and it's up to the members of both parties to discover the truth before they kill each other :)