Way of the Thirsting Reaper

Monks of the Way of the Thirsting Reaper sacrifice much for their power. You lose the ability to regain ki during a short rest, instead gaining the forbidden knowledge to siphon it from the recently deceased. Doing so fills you w/ energy, allowing you to channel far more ki than normally possible, but only for a short time. As you advance in this discipline, you learn to use this extractive process to mend your wounds, & eventually perform it in an instant, ripping your enemy’s ki from its body as you strike a killing blow.

Ki Reaper

When you choose this tradition, at level 3 you no longer recover your expended ki when you finish a short rest, instead, you utilize a short ritual described below. You still recover all expended ki when you finish a long rest.

By concentrating for 1 continuous min next to the body of a creature slain in the last hr, you can extract a portion of that creature’s soul to replenish your ki. You gain a # of ki points = to the creature’s hit dice. Ki gained in this way can exceed your normal max ki. Any ki points above your max are considered temporary ki. They're used 1st when spending ki points, & are lost when you take a long rest, if unspent. Like temporary hp, if you've temporary ki &'d gain more, the higher value replaces the lower 1, they aren’t added together. (For example, if you've 4 temporary ki &'d gain 5 more, you'd have 5 temporary ki, not 9.)

This ability doesn’t function on constructs, & certain creatures might be immune at DM’s discretion. A creature subjected to this ability can’t be brought back to life by anything less than true resurrection or wish.

Once you have used this feature, you must finish a long rest before you can use it again. At level 6 you gain a 2nd use of this feature a 3rd at level 11 and a 4th at level 17.

Death Strike

At 6 level, you can empower your strikes w/ your ill-gotten ki. When you hit a creature with an unarmed or monk weapon attack, you can spend up to 3 ki to deal an additional 1d10 necrotic damage/ki spent. If you use this ability when you deal damage to a creature that has 0 hp, it's killed instantly.

Assimilation

By 11 level your act of extracting a fallen creature’s ki also heals your wounds. When you use your Ki Reaper feature, you also regain 6 hp/ki point you gain. Hp you'd regain past your hp max are instead gained as temporary hp which last until your next long rest.

Swift Harvester

At 17th level, you can extract ki from your fallen enemies w/ ruthless efficiency. If a creature adjacent to you's reduced to 0 hp, you may use your reaction to expend a use of your Ki Reaper, gaining its full benefits instantly. You can only do this once per combat.