Here is the full list of all 17 TANGLEWOOD achievements.
Collect 50 fireflies
Collect 100 fireflies
Collect all fireflies
Kill the Djakk in Chapter 1, Act 4
Kill the Djakk in Chapter 2, Act 3
Survive an encounter with an angry Scirus
Evade a Djakk's bite
Kill Borgus with only two boulder drops
Kill a Demon Swarm with the Lightning ability
Complete the game
Complete the game with all fireflies
Sneak past the Djakk in Chapter 1, Act 3
Coerce a Hogg into getting stuck in three walls
Allow Echo to collect a firefly
Beat Echo in a mine cart race
Evade a Wyrm attack
Kill all Djubb fish in Chapter 8, Act 1