Vordrassil's Seeds and Vordrassil's Sapling

When you have accept 2 new quests move to Grizzlemaw.
Collect 8 seeds
Burn down the tree in the middel of the world tree.

When you are done move back to Amberpine and leave them and pick up the new one.

You are now going to kill the Bear God. This is the last quest of the chain, you will get blue rewards.