The word "reave" means either "to rob" or "to deprive". The Way of the Timereaver Monks call themselves as such because they have learned to manipulate the flow of time and space around them. They meditate on relativity, and just as they might be able to understand on a deeper level the way energy flows through the body, they can understand on a deeper level the way time and space interact and learn to manipulate it.

The practice of the Way of the Timereaver centres around bending time around your foes, and confusing and disorientating their sense of time. Those who study the Way of the Timereaver may sometimes spend aeons honing their craft, as after all, time to them is meaningless.

Flow of the Timereaver

Starting when you take this subclass at 3rd level, you begin to understand the basics of bending time and space around you and around your foes.

Whenever you hit a creature with one of the attacks granted by your Flurry of Blows, you can impose one of the following effects on that target:

• It must succeed on a Wisdom Saving throw, or have it's speed halved.
• It must succeed on a Wisdom Saving throw or it can't take bonus actions, or reactions until the end of your next turn.

Reaver's Restitution

Starting at level 6, you understand even further the ways of time's flow, allowing you to be more precise with how you manipulate it.

As an action on your turn, you may spend 1 ki point to accelerate a creature's body through time. A creature you touch must succeed on a Constitution Saving Throw, or any spell or condition affecting them has it's duration reduced by 1 minute. A creature may choose to fail this save. If a spell affecting the target is affecting more creatures than just the target, the duration is only reduced for the target.

Space-Time Break

Starting at 11th level, your understanding of the space-time continuum becomes more of a mastery. As you begin to master how to manipulate time and space, you begin to further understand just how far you can break it before it's irreparable. 

As an action, you may spend 5 ki points to break space and time around you. When you do this, you may choose one of the following effects:

Fast-forward. Up to three creatures of your choice within 30 ft of you gain the effects of a Haste spell for 1 minute. You are considered to be concentrating on the spell, and have disadvantage on saving throws to maintain your concentration.

Slow-down. Any creatures of your choice within 30 ft of you must attempt a Wisdom Saving Throw. On a failed save, a creature falls under the effects of a Slow spell for 1 minute. You are considered to be concentrating on the spell, and have disadvantage on saving throws to maintain your concentration.

Freeze. Up to three creatures of your choice within 30 ft of you must attempt a Wisdom Saving Throw at advantage. On a failed save, a creature takes psychic damage equal to a roll of your Martial Arts die + your Wisdom modifier, and is stunned until the end of your next turn.

Warp. Up to five creatures of your choice within 30 ft of you must attempt a Charisma Saving Throw. On a failed save, the creature is teleported to an unoccupied space of your choice within 60 ft of the creature. A creature may chose to fail this saving throw.

Suspend. Up to three creatures of your choice within 30 ft of you must attempt a Charisma Saving Throw. On a failed save, a creature disappears between the folds of space and time for 1 minute or until you break concentration (as if concentrating on a spell). While suspended between the folds of space and time, a creature is unconscious and incapacitated. When this effect ends, a suspended creature returns in the space it disappeared from, or if that space is now occupied it appears in the nearest unoccupied space. The creature has no memory of its time in suspension.

Timereaver's Suspension

Starting at level 17, your mastery over time and space becomes near-perfect. Of course, you know better than anyone that there is always more to learn, but you are certain you will have all the time in the world to learn.

When you receive this subclass feature, you stop ageing. Additionally, you gain the ability to accelerate or reverse your ageing, allowing you to appear any age you wish.

Additionally, when damage reduces you or another creature within 60 ft of you to 0 HP, you may use your reaction to grant the target immunity to that instance of damage, rewinding them to the moment before they took the damage. When you do this, you may choose to attempt to suspend the target in time for 1 minute, or until you end it as a bonus action or are reduced to 0 HP. If the target is unwilling they must attempt a Wisdom Saving Throw or be suspended in time. While a target is suspended in time, they have immunity to all damage, don't need to eat, drink, or breathe, don't age, and are blinded, deafened, and incapacitated. They remain visible, but only you have the ability to interact with them in any meaningful way, and they weigh 1/4 their normal weight to you.

After you use this ability, you cannot do so again until you finish a long rest, or spend 5 ki points as part of the reaction.