Here is the full list of all 34 Mable & The Wood achievements.
Unlock the well
Kill the Queen of the Wood
Kill the Guardian of Echoes
Kill the King of Dirt
Kill the Quantum Pilgrim
Kill the Recluse King
Kill the Watcher of Dusk
Beat the Grand Warlock in the caves
Beat the Grand Warlock in the priory
Kill the Grand Warlock in the palace
Get across the collapsing bridge
Get through the cave in
Survive the chase after the tower
Find the lost brother
Collect 1000 diamonds without spending them
Beat the game 1st time
Beat the game a 2nd time
Beat the game a 3rd time
Start the game the 4th time
Standard pacifist ending
100% pacifist ending
Listen to everything that the old lady has to say
Speak to the butler and the maid in the palace, having spoken to their elder counterparts
Find the secret pacifist door in the caves
Collect all of the maps
Survive the priory elevator
Beat the pacifist warlock chase in the priory
Max out health upgrades
Max out magic upgrades
Discover all of the flashbacks
Get carried by the eagle
Meet the nice version of the parishioner
Beat the game without ever dying
Kill a total of 500 enemies