Demon invasion.

I tried playing the Campaigns; before this, I had only played separate missions. I completed the first one—after a total lack of sp in the second half—using army recruitment + darkness + a cloak that dropped from Dragon Utopia. In the second one, everything was going well, but around week 3-4, I started approaching the second city (the snow one, not counting where the 4 heroes start) and saw 2 stacks of 10-12 dragons blocking the path (I had to break through at least one) and a stack of bears. Was this just bad luck with the random spawn, or is it supposed to be like that?