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 all tutorials.
Collected every treasure item.
Collected 10 cabbages.
Went into Avatar State 10 times.
Spirit-bended 200 dark spirits.
Completed the highest difficulty of Pro-bending.
Got 10 Knockouts in Pro-bending matches.
Completed the game on Extreme difficulty.
Maxed out all bending types.
Performed 100 Finishing Moves.
Purchased 12 talismans.
Obtained all combos.
Completed Chapter 8.
Completed Chapter 7.
Completed Chapter 6.
Completed Chapter 5.
Completed a Naga Running sequence without hitting anything.
Countered 100 times.
Went into Clash Mode 10 times.
Dodged 100 times.
Completed Chapter 4.
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.