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