Savage Stalker

As a Bloodletter, you've embraced the chaos and frenzy of battle, wielding your blades with unmatched ferocity. Whether you're hunting down your enemies or defending yourself in the thick of combat, your speed and savagery make you a formidable opponent.

(this is an obvious reference to The Legion from Dead by Daylight. I just thought it would be a cool rogue subclass.)

Feral Frenzy

Starting at 3rd level, you can tap into a primal frenzy, enhancing your speed and agility in combat. As a bonus action, you can enter a Feral Frenzy for 1 minute. During this time, you gain the following benefits:

• Your movement speed increases by 10 feet.
• Whenever you use your action to make a melee attack against a creature, you can make an additional melee attack against a different creature within 20 feet of the original target. This attack does not benefit from your Sneak Attack feature.
• If you reduce a creature to 0 hit points with a melee attack during your Feral Frenzy, you can use your bonus action to move up to your movement speed and make a melee attack against another creature.

Once you use this feature, you can't use it again until you finish a short or long rest.

Blood Sense

Starting at 9th level, you've honed your senses to detect the faintest traces of blood. You have advantage on Wisdom (Perception) checks to detect creatures that are below half their hit point maximum.

Bloodthirsty Prowess

At 13th level, your relentless pursuit of your prey grants you an advantage in combat. During your Feral Frenzy, whenever you make a melee attack against a creature that has taken damage since the start of your last turn, you deal extra damage equal to your sneak attack damage.

Frenzied Assult

At 17th level, your Feral Frenzy reaches its pinnacle. When you enter a Feral Frenzy, you can make an additional attack with a melee weapon as part of the same bonus action. Additionally, the movement speed bonus from your Feral Frenzy increases to 30 feet.