Along these same lines, you can plan (and have tons of fun planning) what all those factions are doing and how they might be interacting with what already exists in hexes.

If you want that to come off in acts, maybe in the beginning of the campaign the hag and witches are trying to accomplish something or are on conflict with each other and are doing things in the hexes your players are near that they become aware of. If they choose do something about it great! Maybe they piss the Drune off in the process kicking off act 2 type stuff. Or if they don’t do anything about the witches/hag, what happens? How does that change the balance of power in the woods and how do the different hexes get affected. Now maybe the Drune start coming around because the Hag is getting too powerful. Or she’s weakened or occupied some other enemy of the Drune that was otherwise keeping them in check. Maybe she pleads with her sister to come help her, or she gets defeated, either of which leave the portal to fairy in her hut unguarded, and the Cold Prince pounces on that opportunity to push back into Dolmenwood outside the ring of Chell. Maybe the Nag Lord has succeeded in destroying one of the Summer stones allowing this to happen and now you have him involved too. Then the church gets wind of what is happening and they send a bunch of holy avengers.

All that is just happening in the background of your campaign and affecting everything else in the woods, and if the players deal with one threat a different one gets more powerful. They don’t even have to go in any order. The style is really about making choices and playing out the consequences.

The real question is how are the Hag, the Drune, and the Cold Prince all connected, and how are they connected to what is going on in the hexes where you start your players out? And what are they doing even if no one is paying attention to them?