Here is the full list of all 8 Roots of Yggdrasil achievements.
Meet Hoenir
Build the Workshop in the Holt.
Complete your first loop.
Build the Greenhouse in the Holt.
Witness Lif and Thrasir's Feelings Sprout.
Complete a loop with 7 cards or less into your Deck.
Complete a loop with 50 cards or more into your Deck.
Have 15 or more curse cards into your Deck.