Rogue Archetype
Bloodletter
Bloodletters are deadly and often sadistic fighters who prefer when their opponents dies from a multitude of bleeding wounds that they cause. Their training and techniques with daggers makes them just as lethal as any well-armed fighter. Bloodetters enjoy cultivating misconceptions about the level of danger the present, and they relish any chance to demonstrate that the most unimposing weapons can be the most lethal. Thus, they are rarely impressed by how mighty their opponents appear.
Lifeblood Specialist
Creatures without blood or that can't bleed, for example undead, plants or constructs, are immune to all of Bloodletter's features, except Bonus Proficiencies.
Bonus Proficiencies
When you choose this archetype at 3rd level, you gain proficiency with the Medicine skill. If you already have proficiency in this skill you gain proficiency in another skill from the rogue skill list.
Bleeding Wounds
Beginning at 3rd level, while wielding a light, finesse weapon such as a dagger, whenever you would deal damage with your Sneak Attack feature, you may choose to create a Bleeding Wound, sacrificing amount of Sneak Attack Dice equal to your Wisdom modifier.
At the start of the targets turn, roll the amount of sacrificed dice. Creature takes necrotic damage equal to rolled result. At the end of its turn, the creature must make a Constitution saving throw to attempt to stop the bleeding. The DC of a saving throw equals to 8 + your Wisdom modifier + your Proficiency bonus. If successful, the target stops all Bleeding Wounds. Creatures can have no more than 1 Bleeding Wound at the same time.
Bleeding Wounds lasts for amount of rounds, equal to your Wisdom modifier or until target succeeds in saving throw.
Bloodlust
At 9th level, You gain advantage on attack rolls made against a targets with Bleeding Wounds. Also, your affinity for blood provides you with skill to track the weakened targets.
You gain advantage to all Wisdom (Survival) checks to track creatures, which current Hit Points are less than maximum. Also, you can sense creatures with less than Half of their maximum Hit Points within 15 feet of you, considered as if you had Blindsight.
Sadistic Nature
At 13th level, whenever a creature that has a Bleeding Wound made by you drops to 0 HP or dies within 30ft, you can use your reaction to preform a sadistic mockery. Whenever you do so, you gain temporary hit points equal to half of your rogue level, rounded down, plus your Wisdom modifier which lasts for 1 minute. While you have temporary hit points granted by this feature, you also gain resistance to psychic damage and you are immune to a Vicious Mockery spell.
Once you use this feature, you can't use it again until you finish a short or a long rest.
Final Slice
Beginning at 17th level, you become a master at pinpointing an enemy’s arteries and weak points. When you perform a Sneak Attack on a target that has a Bleeding Wounds, you can designate this attack as a Final Slice.
Whenever you roll Sneak Attack damage against a creature that has a Bleeding Wound you can force it to make a Constitution saving throw against your Bleeding Wound DC. On a failed save, the creature takes extra necrotic damage equal to half of your rogue level, rounded down and all Bleeding Wounds that affects it lasts from 1 minute and can't be ended earlier by any means.
Once you use this feature, you can't use it again until you finish a long rest.