[RPG] What’s the closest RAW build possible to the Gray Mouser in 5e

character-creationdnd-5e

I am of course referring to the legendary figure of Fritz Lieber's Lankhmar series (one of the things Gary Gygax said was his inspiration to invent D&D).

I am assuming this character is so off-the-hook awesome that I cannot see any way to make him using strictly RAW, but what's the closest we can get?

Some things to keep in mind:

  • His acrobatics, stealth and persuasion are incredible (especially acrobatics)
  • His swordsmanship is fantastic, in a finesse-sort-of-way (rapier?), and when combined with a successful acrobatic move he can hit almost anything
  • He is devastating with a sling, e.g. can knock someone out or do great damage (a thing which seems outside the RAW in 5e)
  • He has a custom-made bodysuit that enhances stealth, and he is very hard to hit in melee (almost un-hittable!) despite that he has no armor or shield beyond this
  • He has some low-level arcane spellcasting abilities
  • While he is not immune to being charmed, he is fairly resistant to it

Those are the essentials, and here are nice-to-haves:

  • Race is human
  • Magic is limited mainly to illusions (less magic than an Arcane Trickster has)
  • Acrobatic-based swordplay (to-hit improves somehow when using acrobatics)
  • Can use a sling effectively at longer range, compared to a typical character

There may be other features I am overlooking from Lieber's material, but those are the high points. What's the closest you could come in RAW?

Best Answer

A human Fighter/Rogue (Arcane Trickster) of at least 8th level total, perhaps level 14 or higher

According to the Q&A with Gary Gygax, part 5 forum thread in 2004:

The Thief was based on Jack of Shadows (Zelazny) and Cugel (Vance) with a touch of REH’s Conan, rather than solely on the Gray Mouser. Mouser was too good a swordsman to serve as the pure model.

However, Gygax was talking about the D&D of his era, and the rules have changed much since then. Based on your requirements, the Rogue class (which in Gygax's D&D was called the Thief) with the Arcane Trickster subclass is a suitable match:

  • Acrobatics, stealth and persuasion: All three of these are literally class skills for the rogue. The rogue's Expertise ability at 1st and 6th level allows their proficiency bonus to be doubled for these skills, and Reliable Talent (11th level) also extends this ability.
  • Fantastic swordsmanship: The rogue is proficient with the rapier, as well as shortswords and longswords. D&D 5e no longer gives the fighter a higher base attack bonus than the rogue, so this class imposes no penalty.
    • Optional acrobatic swordplay: Tricky to model in D&D, but the most readily available solution is to drop at least a single level in fighter and adopt the Dueling fighting style which grants +2 to damage while fighting in his unique style with no shield. A level 3 fighter (Battle Master) gains unique and clever maneuvers, but this may be pushing it. I'm not aware of any official feat or option in this particular edition of D&D that specifically gives a combat bonus for using the Acrobatics skill.
  • Devastating with a sling: The rogue has sling proficiency (as a simple weapon) and can gain Sneak Attack if he has advantage on the attack roll, even if he is not hidden from the opponent. A high level rogue can deal substantial damage with sneak attack.
    • The optional requirement of long range with a sling can be met with the Sharpshooter feat, which extends range and the ability to hit through cover. Currently, there's no rule which allows a nonlethal knockout with a ranged weapon (although any character may do this with a melee weapon).
  • Custom bodysuit and unhittable: He would require magic items for this in D&D: magical leather armor, a cloak of displacement, and a naturally very high or magically-enhanced Dexterity. For a high-level character, these magic items are plausible.
    • Uncanny Dodge (5th level rogue ability) halves damage from attackers the rogue can see.
    • To meet the optional requirement of the character being human, with the human starting ability score bonus and ability score improvement at every 4th rogue level, he could still have superhuman Dexterity. (If you're willing to forgo the human requirement, an elf would also have naturally increased Dexterity.)
  • Low-level spellcasting: The Arcane Trickster roguish archetype gains 1st level arcane spells at level 3, 2nd level spells at level 7, and 3rd level spells at level 13. This is low level magic for the character level, if we assume the character is below 18th level.
    • Mainly illusions: An arcane trickster who only chooses illusions, even if the class doesn't enforce this, is still a valid build. The first level spell silent image creates illusion with no sound; second level minor image alllows image or sound; the third level major image adds other sensory effects and the illusion can move around. If major image is beyond his ability then he should not be above 12th level; otherwise, level 14 or 15 would be possible.
  • Charm resistance: A high-level character with high Wisdom would have high saves, and magic items may enhance that further. If it's not required to make the character a human, an elf of any sort or half-elf is resistant but not immune to being charmed.
    • To meet the human optional requirement while still resisting charms, he could spend his first feaat (variant human feat at 1st level ability) on Resilient to increase his Wisdom by 1 (which may already be high to begin with) and grant proficiency in Wisdom saves. If Gray Mouser is really high level, the 15th level rogue ability Slippery Mind gives proficiency in saving throws, but he could of course just take the Resilient feat at an earlier level.

On a historical note, according to Dragon Magazine #70 (February 1983), Gray Mouser would be a a very high level multiclass fighter/thief. This is consistent with Gygax's opinion that Gray Mouser is like a Thief but better at swordfighting.

Thanks to @DavidCoffron, @KorvinStormast, @DarthPseudonym and @sharur for suggestions in the comments.

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