Here is the full list of all 8 Roots of Yggdrasil achievements.
Complete your first loop.
Build the Workshop in the Holt.
Have 15 or more curse cards into your Deck.
Build the Greenhouse in the Holt.
Meet Hoenir
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.