[quote=IncredibleBee]
Except there's no reason for any character to work together; half of us haven't even met each other, and a good other chunk are more likely to just leave Estermere.Furthermore, a demon invasion is something you lead up to, not something you use as a lead.
[/quote]

For a Demon Invasion. You hear weird stuff, you find cultists. Say, you know how there was that Creepy Kid at the Graveyards? Surely they'd know stuff about this, and the Priesthood certainly would think they are related to the Cult.

And it turns out the Cult was using some Gnolls as shock troopers and framing a certain clan. The cult may have taken a fascination with a certain new child with red eyes and took them to their lair. Etc. 

You need to establish these connections between the players before activating MEGA EVENT. Because, as Bee said, [i]why[/i] would we help each other when we don't know each other? OR why stay when you don't have a connection to the town?