Silent Killer (5e Feat)

Prerequisites: Dexterity 13 or higher
You can deliver a lethal strike while keeping yourself undiscovered. You gain the following benefits:

You gain proficiency in the Stealth skill. If you are already proficient in the skill, your proficiency bonus is doubled for any ability check you make that uses the Stealth skill.

When you make a Dexterity (Stealth) check, you can choose a hostile creature you can see within 120 feet of you. As long as you stay hidden, the chosen creature have disadvantage on Intelligence (Investigation) or Wisdom (Perception) checks to spot or notice you. You cannot use this feature if you have disadvantage on Dexterity (Stealth) checks.

When you attack a surprised creature and reduce it to 0 hit points, you can use your reaction to perform the Hide action. You cannot use this feature if you have disadvantage on Dexterity (Stealth) checks. Your footsteps are now silent.