When you use the spectral blade subclass, you can kneel and get a headshot to go invis. While invis if you melee a boss it applies what essentially is hunter's version of melting point. They both offer the same amount of a damage buff, but with the hunters you can keep applying it a few times before the timer runs out. Melting point is a one time deal. Once the timer runs out just kneel, get another precision kill, and repeat.