TEXT: 5/1/2019
  Rogue: Assassin (Revised, HB) | GM Binder
  https://www.gmbinder.com/share/-LdbtzMhuvWxxE2_RDeW
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  Assassin
  Y
  ou focus your training on the grim art of death.
  Those who adhere to this archetype are diverse:
  hired killers, spies, bounty hunters, and even
  specially anointed priests trained to exterminate
  the enemies of their deity. Stealth, poison, and
  disguise help you eliminate your foes with deadly
  efficiency.
  Bonus Proficiencies
  When you choose this archetype at 3rd level, you gain
  proficiency with the disguise kit and the poisoner's kit.
  Mark for Death
  At 3rd level, you may spend an action to study the vitals of a
  single creature you can see, marking it for death. For up to 1
  hour with concentration (as if you were concentrating on a
  spell), you know the marked target's hit points at all times
  until you lose sight of it, mark a different creature, or lose
  concentration. You can only have one creature marked for
  death at a time.
  Assassinate
  Starting at 3rd level, you can assassinate your marked target if
  its hit points are low enough. Using your Cunning Action, you
  can make a weapon attack against a creature marked for
  death, which will reduce its hit points to 0 on hit. You can do
  this as long as all the following conditions apply:
  The target has no more than 2 × your rogue level in hit
  points before the attack
  The attack does not have disadvantage.
  Modus Operandi
  At 9th level, you gain one of the following features of your
  choice.
  Poisoner's Expertise
  Your proficiency bonus is doubled for any ability check you
  make that uses a Poisoner's Kit or to recover resources
  needed to craft potions.
  Poisons you craft have their saving throws equal 8 + your
  proficiency + your Intelligence modifier. When you administer
  an injury poison while hidden, the target has disadvantage on
  the first saving throw against it.
  Impersonator's Expertise
  Your proficiency bonus is doubled for any ability check you
  make that uses a Disguise Kit or relies on a disguise you have
  created with a Disguise Kit.
  You can easily conceal up to two light weapons within each
  of your disguises, as long as there is enough material to cover
  them. While wearing an appropriate disguise, you benefit as if
  you were hidden on weapon attacks against creatures
  deceived by your disguise.
  Vendetta
  Starting at 13th level, you have advantage on weapon attacks
  against your marked target if within 15 feet of it, there are no
  creatures friendly to it that are not incapacitated or surprised.
  When you use Uncanny Dodge, you can mark the attacking
  creature for death as part of that reaction.
  
  5/1/2019
  Rogue: Assassin (Revised, HB) | GM Binder
  https://www.gmbinder.com/share/-LdbtzMhuvWxxE2_RDeW
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  Killing Technique
  At 17th level, you gain of the following features of your choice.
  When a target must make a saving throw against this feature,
  the DC is equal to 8 + your Dexterity modifier + your
  proficiency bonus.
  Garrote
  You can fashion at least 2 feet of wire, rope, cable, or anything
  of the sort into a garrote, which you treat as a light, two-
  handed improvised weapon you are proficient with. On hit, it
  applies Sneak Attack, as long as you do not have
  disadvantage, and grapples the target. While you have a target
  grappled in this way, you can repeat the attack on the grappled
  target as an action. If you are hidden from the target when you
  attack it with a garrote, all its subsequent attempts to escape
  the grapple are made with disadvantage until it escapes.
  If an attack with the garrote hits and the target has a neck
  that can be entirely wrapped by it, the target must succeed
  Constitution saving throw or immediately begin to suffocate. If
  it was marked for death, it has disadvantage on the saving
  throw. Whether or not it succeeds, the target cannot speak or
  cast spells with the verbal component, thus you may remain
  hidden from other creatures until the target escapes.
  Additionally, a garrote can be coated with one dose of a
  contact or injury poison, which will be administered on hit.
  Plunge
  If you fall at least 10 feet immediately before making a melee
  weapon attack, that attack deals 1d6 additional damage for
  every 10 feet you fell. If the attack hits, the target must
  succeed a Constitution saving throw or fall prone. If you are
  hidden during this attack, the target has disadvantage on the
  saving throw.
  Additionally, your weapon attacks critically strike if they hit
  a prone target you have marked for death.
  Eviscerate
  When you hit a target marked for death with a weapon attack
  and its hit points are no more than 3 × your rogue level, it
  must succeed on a Constitution saving throw or be
  assassinated, as long as all other conditions of the Assassinate
  feature are met.
  When you assassinate a creature that does not have
  Incorporeal Movement and is not a construct, you deliver the
  final blow with a graphic display of gore. Each creature hostile
  to you that can see or hear you must succeed a Wisdom
  saving throw or be frightened of you for 1 minute. An affected
  creature can repeat the saving throw at the end of its turn to
  end the effect. If a target's saving throw is successful or the
  effect ends for it, the target is immune to being frightened in
  this way for 1 hour.
  Image Sources
  1. Trung TH
  2. Russell Dongjun Lu
  When a Plan Comes Together
  Jarod, an 18th level assassin rogue, prepares to
  execute his target. His party is tasked with
  eliminating a gang of bandits terrorizing the city,
  which are unwittingly gathered before him. For this
  job, he prepares an injury poison and applies it to
  his main-hand dagger.
  He perches on the scaffolds above his target, an
  archer that is sure to be the most troublesome.
  While Jarod awaits the signal from his party, he
  studies his target's weaknesses, marking it for
  death.
  The signal is given, and Jarod's party surprises the
  bandits. Able to make the plunging attack, he
  attacks the archer with his main-hand dagger.
  Because he was hidden from the archer, it has
  disadvantage on the Constitution saving throw
  against falling prone. Jarod also has Poisoner's
  Expertise, so the archer also has disadvantage on
  the saving throw against the injury poison.
  The archer falls prone and has 34 hit points after
  receiving damage from the poison. Because the
  archer is marked and has 34 hit points, which is
  less than 2 × Jarod's rogue level, it can be
  assassinated. With his Cunning Action, Jarod makes
  the attack with advantage, since the archer is prone.
  The attack hits, and the archer instantly dies.
  
SOURCE: textdata/thevault/Dungeons & Dragons [multi]/5th Edition (5e)/3rd Party/Homebrew/Rogue Assassin.pdf