Ghost Assassin (5e Subclass)
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Ghost Assassin, Fiend of the Ethereal
Members of the Ghost Assassin Syndicate, depending on who you ask, are either an order of assassins or specters of death itself. The members of this guild preserve ancient techniques, passed down through generations of recruitment, by which a person becomes a spirit, and how that spirit can kill. Addicted to the ethereal, they see themselves as the ultimate assassins in which they slay in broad daylight, and escape invisibly into the air.
Beginning when you choose this archetype at 3rd level, you get a number of Specter Points to be able to tap into the ethereal. The starting points are equal to 1+ either your Intelligence, Wisdom, or Charisma (pick one, this never changes once chosen) modifier. At level 9, double those points; at level 13 double your points again; at 17th level double your points for the last time. You regain all your Specter points with a long rest and only half with a short rest.
Starting at level 3 when in combat as a bonus action, you can become invisible for up to 10 rounds, or until you make an attack or cast a spell. Outside of combat you can become invisible for 1 min or until you make an attack or cast a spell. This ability uses 1 Specter Point per use. At level 9, as a free action you can use a Specter Point to remain invisible when you make an attack or cast a spell. Then, starting at 13th level, by spending 1 Specter Point as a free action you can become ethereal while you are invisible. When ethereal you can move through creatures and objects as if they were difficult terrain as well as move up or down or any direction as if floating treating this ethereal movement as difficult terrain; you may move normally through normal areas when ethereal. While ethereal you cannot take damage from anything outside of the ethereal plane nor can you do damage or cast spells outside of it. You can see only in b&w and through objects like x-ray vision but only a maximum distance of 60 ft when ethereal; magical darkness or any magical effects due to sight or sound still effects the ethereal player as normal. When dropping out of ethereal you also become visible but can as a free action spend a Specter Point to remain invisible as you phase back in. Lastly, at 17th level, you no longer have to treat any of your ethereal movement like difficult terrain.
By 3rd level, you strike terror into your victim's heart when you disappear out of thin air after delivering a precise, crippling blow. Whenever you hit a creature with a sneak attack that ends with invisibility on yourself, you can cause the target to make a Wisdom saving throw (DC equals 8 + your proficiency bonus + your Dexterity modifier) or become frightened of you giving you advantage on all attack roles against that target and giving them disadvantage on all attacks against you for the duration they are frightened of you. The target remains frighten until they make a successful save but can repeat the saving throw at the end of each of its turns. Once a creature has been frightened by this ability, it can't be frightened by it again for 24 hours. At 9th level you gain 2d6 of psychic damage to successful hits against creatures frightened by you with this ability. At level 13 it increases to 3d6 and at 17th level 4d6.
By 9th level, you have trained yourself to make almost no noise while stalking your targets even when not ethereal and can move at full speed or dash action without stealth penalty. You have advantage on Dexterity (Stealth) checks involving sound, and you cannot be detected by creatures using tremor sense. You also gain Darkvision to 60 ft if you didn't already have it, if you already have darkvision double the range.
At 13th level you gain the ability to see through magical darkness and you can cast the spell darkness as a bonus action on yourself with a 30 ft radius by spending three Specter Points. You can also cast the spell chill touch at will as a standard attack action using one Specter Point but it only has a range within the radius of your darkness spell doing 3d8 of necrotic damage with a successful hit; any target that receives necrotic damage from your Chill Touch additionally makes a Wisdom save (DC equals 8 + your proficiency bonus + the modifier chosen for Specter Point calculation) and on a failed save you regain a number of Specter Points equal to half the necrotic damage dealt rounded down. Darkness does not take any concentration but only lasts for 5 rounds or 30 seconds; you can dispel your darkness spell at will or is automatically dispelled if you take any damage or become ethereal. At level 17 darkness can last up to 10 rounds or one minute, darkness but not chill touch can be cast ethereally (an additional Specter Point must be spent to stay ethereal) effecting the normal plane, and necrotic damage increases to 6d8.
At 17th level, no target can hide from your sight. You gain the effects of the see invisibility spell at all times.