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