Monks that follow the way of the Faceless One, serve the many faced God as his assassins and instruments of divine retribution. They give up their individuality becoming no one, so they in turn can be anyone and therefore become masters of Death. 

ASSASSINATE

Starting at 3rd level, you are at your deadliest when you get the drop on your enemies. When you use Flurry of Blows against a creature that hasn't taken a turn in the combat yet you have advantage on those attack rolls and any melee hit in those attacks is a critical hit.

THIEF OF FACES

At 6th level, you gain the ability to adopt a humanoid's persona. When a humanoid dies within 30 feet of you, you can magically capture its face using your reaction. You retain this face until you use it or you finish a long rest. By using 300 gp worth of ingredients and a short rest, you can preserve the face in a box that looks like a wood-paneled bird cage, preventing the face from decaying until used.

You can use the face as an action. When you do so, it vanishes, magically transforming into a disguise that appears on you. You now look like the dead person, but healthy and alive. This disguise lasts for 1 hour or until you end it as a bonus action.

While you're in the disguise, you gain access to all information that the humanoid would freely share with a casual acquaintance. Such information includes general details on its background and personal life, but doesn't include secrets. The information is enough that you can pass yourself off as the person by drawing on its memories.

Another creature can see through this disguise by succeeding on a Wisdom (Insight) check contested by your Charisma (Deception) check. You gain a +5 bonus to your check.

Once you capture a face with this feature, you can't capture another one with it until you finish a short or long rest.

HASTEN THE PASSING

Starting at 11th level, your touch can channel the gift of death into a creature. As an action, you touch one creature within 5 feet of you, and you expend any number of ki points. The target must make a Constitution saving throw, and it takes 2d6 necrotic damage per ki point spent on a failed save, or half as much damage on a successful one. This counts as a monk attack for the purpose of Martial Arts.

REJECTION OF THE GIFT

At 17th level, your service of the Faceless God cannot be stopped by blade or arrow.  When you are reduced to 0 hit points and you have no ki, you can use your reaction to regain half your ki and hit points.

After you use this feature, you cannot use it again for a week.