mjhjmtu

I like crossbows as a concept. There's just something about the loading and the aiming and the thunk. What I don't like as much are rapid-firing automatic crossbows or the kind of machinegunning that Crossbow Expert lets one do. Unfortunately (for me), 5E is built around martial classes doing two to four attacks per Attack action which just... doesn't worth with a Loading weapon.

That said, I'd like to make a character for who doing that one shot per turn is actually a viable use of their turn, rather than something you do when your preferred options ran out (for example, out of spell slots and your damaging cantrips don't work because of immunity/antimagic etc).

Ultimately, I'm looking for something similar to, say, a gish using one of the SCAG cantrips to attack once with their weapon of choice for good damage. And preferably not something that takes action+bonus action+concentration+spell slot to deal half the damage of a same level fireball.

How about a Rogue?

Since Sneak Attack damage only applies to one hit per turn, there's only limited benefit to getting additional attacks (namely getting a second chance to hit), but rogues get lots of useful ways to use their bonus action outside of Two Weapon Fighting. Since the feature is built around getting a single strong attack each round, the damage of Sneak Attack is designed to scale to be (roughly) competitive with classes that get additional attacks.

Sneak Attack

Beginning at 1st level, you know how to strike subtly and exploit a
foe's distraction. Once per turn, you can deal an extra 1d6 damage to
one creature you hit with an Attack if you have advantage on the
Attack roll. The Attack must use a Finesse or a ranged weapon.

You don't need advantage on the Attack roll if another enemy of the
target is within 5 feet of it, that enemy isn't Incapacitated, and you
don't have disadvantage on the Attack roll.

The amount of the extra damage increases as you gain levels in this
class, as shown in the Sneak Attack column of the Rogue

https://roll20.net/compendium/dnd5e/Rogue#toc_5

You would need to find a way to reliably qualify for sneak attack damage each turn, but that's actually not that hard as long as you have melee fighters in your party since firing at an enemy that is within 5 feet of one of your allies grants you Sneak Attack damage.

In 5e there are no penalties for firing into melee, so you don't have to worry about that. There is the risk of an enemy getting cover from you ally or another enemy, but taking the Sharpshooter feat lets you simply ignore this cover. It also removes disadvantage from long range (allowing you to Sneak Attack from 320/400 feet away with a light/heavy crossbow) and gives you the option to add a +10 damage to your attacks in exchange for -5 to hit (generally a risky option for a rogue, since a miss robs you of sneak attack damage):

Sharpshooter

You have mastered ranged weapons and can make shots that
others find impossible. You gain the following benefits:

Attacking at long range doesn't impose disadvantage on your ranged
weapon attack rolls. Your ranged weapon attacks ignore half cover and
three-quarters cover. Before you make an attack with a ranged weapon
that you are proficient with, you can choose to take a -5 penalty to
the attack roll. If the attack hits, you add +10 to the attack's
damage.

http://dnd5e.wikia.com/wiki/Feats#Sharpshooter

As a rogue you're limited to the Light Crossbow (1d8) or the Hand Crossbow (1d6). If you really want the Heavy Crossbow (1d10), your options include:

1. Multiclass (1 level of fighter, barbarian, ranger, or paladin give martial weapon proficiency)


2. Take the Weapon Master feat using an ASI, or at first level with Variant Human


3. Ask your DM about using the optional training rules (DMG 231) to gain proficiency.

A few approaches I found on my own but didn't really appeal to me.

• PHB Beastmaster ranger - your Action becomes one pet attack and one own attack - I'm not sure if Beastmaster and valid belong in the same sentence, though, and the covenant version doesn't work this way.


• Eldritch Knight - use some manner of cantrip (at 7th) / spell (18th) and shoot the crossbow... once... instead of attacking four times since I'm a Fighter in the first place...


• College of Valor Bard - the same as above! ... at 14th level. On a class that's already starved for Bonus Actions.