Please help, one of the red creatures emerging from the portal has occupied a castle (the one in the center of the map).
Then it left the castle, and I defeated it.
But I can't reclaim the castle; it's glowing red, but I can't attack it.

I'm placing four heroes, all Necromancers, including Ornella, in the magic circles, but nothing happens, probably because one of the castles is red.
What should I do?

In the forest on the map, there's a red neutral creature in one location (maybe I need to reach it???), but I can only get to it through a portal, and I don't know where the entrance is.

Please help. What should I do?