well, there's a performance boost with 5 castles, so I wouldn't waste turns) somewhere around the 7th month, if the hero enters the Dungeon, the forces will be roughly equal. If you delay, the consequences will be unpredictable.
Hey, I found some Furies surrounded by 3 packs of Wind Dancers (and red dragons nearby). And the approach is from the dragons' side, right?)
because you can't attack them from the other side.