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