Roguish Archetype: Deadeye
The Deadeye is a rogue who stalks their targets with patience, brutal accuracy and dark powers. They use long bows and heavy crossbows to snipe at a long range, marking targets to harass them with harmful effects. They can manipulate darkness and shadows which grants them additional abilities.
Bonus Proficiencies
When you choose this archetype at 3rd level, you gain proficiency with the poisoner's kit, the longbow and the heavy crossbow.
Kneel
Starting at 3rd level, you can use your Cunning Action to Move at half your speed to behind suitable cover (cover that you can shoot over while kneeling behind it, such as a ship's railing, a large rock, or a turned over table) and then Hide.
Example Kneeling Cover 
Deadeye's Gaze
Starting at 3rd level, you can mark a target that you can see as a Bonus Action. The first time on your turn that you hit the marked creature with a weapon attack, you gain a point of Malice. You can have up to 3 points of Malice at any time. When the target of your Malice is reduced to 0 hit points or is otherwise removed from combat, the mark is removed and you lose your current points of Malice. If you move your mark to a different target you also lose all your current points of Malice.
You can use your Malice to gain access to the following maneuvers in combat. DC's for your Maneuvers = 8 + your proficiency bonus + your Dexterity or Intelligence modifier (your choice). At 3rd level, you know the Deadly Aim maneuver plus 2 other maneuvers of your choice. At 7th, 10th, and 15th level you learn 2 additional maneuvers of your choice. Each time you learn new maneuvers, you can also replace one maneuver you know with a different one. You can only use one maneuver per attack.
Malice Maneuvers
Deadly Aim
When you hit a creature with a weapon attack, consume all your points of Malice and deal an extra 1d6 damage for each point. This damage increases to d8 at 5th, d10 at 11th, and d12 at 17th level.
Binding Shadow
When you hit a creature with a weapon attack, you can expend 1 to 3 points of Malice. The target must make a strength saving throw or become grappled by shadows for a number of rounds equal to the number of Malice spent, or until they make a successful Strength (Athletics) check against your malice save DC as an action on their turn.
Double Tap (Double Slice)
As a bonus action, consume 2 points of Malice and make a weapon attack. You cannot spend additional Malice on this attack nor does it grant Malice.
Death's Retreat
When you hit a creature with a weapon attack, you can spend 1 to 3 points of Malice to magically teleport 10-feet per point into an area of shadows in an unoccupied space that you can see.
Cursed Shot (Cursed Slice)
When you hit a creature with a weapon attack, you can spend 1 point of Malice to put a shadow curse on the creature, bringing misfortune to your target. Until the end of the creature's next turn they have Disadvantage on all Attack Rolls and Ability Checks.
Mercy
As a Bonus Action, you can move your Deadeye's Gaze to a new target while retaining your Malice points.
Iron Sight
As a Reaction to being hit by an attack but before the damage is dealt, you can spend 1 to 3 points of Malice to increase your Armor Class by 1 to 3, if your new AC would cause the attack to miss then it misses.
Shadow Flare
When you hit a creature with a weapon attack, you can spend 1 to 3 points of Malice. The target must make a Dexterity save or be outlined in a crimson, sapphire or violet light (your choice) for a number of rounds equal to the number of Malice spent and the affected creature can't benefit from being invisible.
Shadow Gust
When you are the target of a melee weapon attack, you can spend one point of Malice to have the attacker make a Strength saving throw, or else they are pushed five feet away from you.
Skirmisher's Shot (Skirmisher's Slice)
When you hit a creature with a weapon attack, you can spend 1 point of Malice to distract the creature, giving your allies an opening. The next attack roll against the target by an attacker other than you has Advantage if the attack is made before the start of your next turn.
Collateral Damage
Starting at 9th level, as a reaction when a creature marked by your Deadeye's Gaze dies, you may trigger a burst of shadow energy against each creature within 5-feet of the marked creature forcing them to make a Dexterity save. On a failed save, the creature takes 1d8 necrotic damage for each point of Malice you currently have built, or half damage if the save succeeds.
Shadow Meld
Starting at 13th level, you can hide in areas of darkness or dim-lighting. When you hide in such an area you are Invisible until you Attack or take another Move or Dash action. When you are hidden in the shadows your voice becomes deep and tenebrous. You gain Advantage on Intimidation checks made from the shadows (the target only needs to hear your voice) and, if the target is marked by your Deadeye's Gaze, you may apply your current points of Malice as a bonus towards the check (using Malice in this manner does not consume it).
One in the Chamber
Beginning at 17th level, when you mark a target with Deadeye's Gaze you automatically gain 1 point of Malice if you don't already have any, and you can immediately make a Dash as part the same Bonus Action.