Here is the full list of all 30 The Legend of Korra achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Won a Face-Off in a Pro-bending match.
Completed the highest difficulty of Pro-bending.
Got 10 Knockouts in Pro-bending matches.
Collected 10 cabbages.
Completed the game on Extreme difficulty.
Collected every treasure item.
Purchased 12 talismans.
Maxed out all bending types.
Completed all tutorials.
Obtained all combos.
Spirit-bended 200 dark spirits.
Performed 100 Finishing Moves.
Countered 100 times.
Went into Avatar State 10 times.
Completed Chapter 8.
Completed Chapter 7.
Completed Chapter 6.
Completed Chapter 5.
Completed a Naga Running sequence without hitting anything.
Completed Chapter 4.
Dodged 100 times.
Went into Clash Mode 10 times.
Completed Chapter 3.
Used your first equipped item.
Jumped 100 times.
Entered the Collection Screen for the first time after finding a treasure.
Equip your first item in Korra's Room.
Bought your first item at the shop.
Completed Chapter 2.
Completed Chapter 1.