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