I'm not sure if you already have a 3rd arc planned for Grizzleheim but I thought I would suggest one. In Nidavellir you have the sun and moon doors, I thought you could have them linked to the Seedlie and UnSeedlie courts (and yes those are not typos).
It would be an area that could have different levels to them but would be where the treants and other plant-men would be from originally. They could be based on the Seelie and Unseelie courts for the Fae. Just a thought.
