Here is the full list of all 45 WREN achievements.
Upgrade livestock to level 4
Upgrade the farm to level 4
Upgrade the strange tree to level 4
Take 250,000 Steps
Use 1,000 Mana
Defeat the Sirens
Take 100,000 Steps
Use 500 Mana
Take 3,030 Steps
Till the soil
Walk 1 Mile
Walk 10 Miles
Walk 50 Miles
Walk 100 Miles
Walk 250 Miles
Walk 500 Miles
Run 1 Mile
Run 10 Miles
Run 50 Miles
Run 100 Miles
Run 250 Miles
Run 500 Miles
Ride 10 Miles
Ride 50 Miles
Ride 150 Miles
Ride 500 Miles
Ride 1,000 Miles
Ride 2,500 Miles
Defeat the Pixie
Use 5,000 Mana
Eat a Piece of Pie
Defeat the Ogre
Take 1,000,000 Steps
Defeat the Wyrm
Use 10,000 Mana
Upgrade fishing to level 4
Use 25,000 Mana
Find the lost Halloween costume
Recover the presents
Walk 1000 Miles
Ride 5000 Miles
Run 1000 Miles
Take 2,000,000 Steps