Help!!!!
You play the game.
But in all seriousness, they’re unlocked from day one. Backstab is available when you’re in stealth and replaces your normal #1 ability(Double Strike). Lotus Strike is the 3rd in a chain attached to your ‘1’ key. Basically its: Double Strike → Wild Strike → Lotus Strike. Watch the little thumbnail change as you hit the enemy with each dagger strike or enter stealth.