So, the final fight was us four (the cleric, the rogue/monk, me the ranger and the NPC smith/fighter) against a fighter, a cleric, a mage and a giant frog. The Evil Botanist (the cleric) wanted us to return his book to him, which we of course refused. I asked him about the tree, and it seems that this trick with the apples will be mightily hard to reproduce: a vampire was staked with a stake that was still alive, resulting in some sort of undead tree. OK, so the healing and poisoned apples are pretty cool, but I don't think I would want to try and stake a vampire for that. Also, if you sat down against the tree, it would dominate your life ever after (which is what happened to the other people present).
So, after some carefully chosen insults, we came to blows. The fighter was neutralised with a Hold Person from the cleric, the mage was quickly dismissed as was the giant frog. That left only the cleric, and he gave us some trouble with his Entangle spell (plants grow out of the ground that grab you and hold you in place -- you can't attack and have to succeed in a Strength check with difficulty rating of 20, quite effective...) but when the smith and me broke free he was quickly dismissed.
After that we chopped down the tree and pretty much everything in the cave died. The end.
We gained another level, as well -- so now I'm a level 4 ranger, and with my higher Wisdom stat, I can now cast one level 1 spell per day! Guess what -- Entangle is a level 1 spell... Hmmmm...
I also need to choose an animal companion (as some sort of familiar), I am considering a badger.