Mark of the Ninja

Complete the new Special Edition level.

From the level select menu, tap to go to Dosan's Story mission; A Tale From the Past. Completion of this level is required to unlock the items needed for the other DLC achievements, so this will be what you want to do first. The level acts as a pretty good introduction to the new abilities, and tests your ability to efficiently, and stealthily, take out and terrify enemies.