just discovered this a few days ago, really enjoying reading through it all, very well written! I just had a couple questions on a few parts:

For the encounter table, should I be rolling a reaction for each of these, or should some be considered always hostile?

I'm unclear on Ultar's role in the game with respect to the party. The story of the lost war is a good background for how the forest formed, but somehow he's still alive and fighting? Fyr is obviously the primary villain (destroy her heart to stop the forest spreading), so is Ultar an ally? Should he (or his soldiers) be expected to accompany the party to the bleeding heart? 

It is also mentioned that the gaunt soldiers are fighting Fyr's forces, but doesn't explain who those forces are. The barkfolk seem to be passive creatures who are aligned with Fyr, but not fighting for her. 

Hi Bearklaw

Thanks for the questions. 

1. It is ultimately up to you whether reactions should be rolled each time or not. If an encounter's reaction is obvious to me (like if someone is already an enemy), then I go with I think is best. If it isn't obvious to me, I let the dice decide. Most of the time it isn't so obvious and I think that makes things more interesting.
2. Ultar isn't really a person anymore. He is a force of will kept alive through supernatural means. In his description it says, "He cannot remove his armour, for there is nothing inside except a raging will for vengeance." All he wants is to destroy Fyr's heart, and he will do anything to achieve that. If the PCs can convince him that he needs their help, then he would ally with them. If he sees them as threatening his chances at destroying the heart, then he might mark them as an enemy. For a more behind the screen view on things, he is the unstoppable force and Fyr is the immovable object. They are opposites and in stalemate.  
3. Yes, I think I do need to define her forces a little better, but they are all the "dark forces of the forest". This equates to all the creatures and things that have been trying the kill the PCs. I had in mind that the barkfolk can be radicalised to fully side and fight for Fyr, unless convinced otherwise.