Demon invasion.

There's a funny thing in the last mission of the campaign. After a certain point, the Necromancers stopped coming. Mages didn't either, they didn't even buy a hero (maybe I killed all the heroes, and they don't have a tavern). Necromancers probably don't come simply because they don't have enough wood to buy a boat (they should have gold, though, since there's a Necropolis nearby). Here's the army they managed to gather: http://c2n.me/3Q03pYO. I checked the tavern; their army consists of 248-436-682-1178-1922-2480-3411 (+2 heroes with 1 archer-skeleton each). They have 19 wood and ore, 6k gold, and 26 artifacts. Behind them is a Library. Want +4 stats? Take down the Necromancer!) They have Sandro's Cloak, so I'll take the Library. And in the end, you have to defeat either a garrison or 10k Titans at a one-way portal, or are those Titans going to leave?