Building a Monk/Warlock, One Step at a Time

[Thundersteel]

So I've been fiddling around with Monk/Warlock builds. I know they suffer from MADness, but they have some fun little synergies and, moreover, are my two favorite classes in 5th ed. It seems I have a weakness for bundles of weird miscellaneous powers.

In terms of concept, it's almost hard not to circle around the "brooding edgelord assassin" drain, and honestly I think I'm a witty enough roleplayer to make that work without it being noxious or overly affectatious.

In terms of mechanics, it's mostly focused on charging up for a round or two, then throwing giant pools of nova damage by combining flurry of blows with hexes. Bad news, it's something that doesn't switch between targets well, good news, it's all based on short rest recovery abilities, so as long as you eat lunch between deathmatches you can do it again later that day.

In terms of race, it partially depends on what the GM will let me get away with. Wood Elf gives a whole mess of useful abilities (bonus movement, bonus sneakiness, longbow proficiency). Drow works just as well stat-wise and gives you that bonus casting of Darkness 1/day, and is also goth AF/thematically appropriate. That sunlight penalty might be a huge impediment with some GM's, but the half-drow variant in SCAG gets around that.
The feral/winged Tieflings variants in SCAG give decent stat bonuses and let you f-bombing FLY which is hard to pass up on.

In most cases, I can end up with something that looks like this:
Str 8
Dex 16
Con 14
Int 8
Wis 14
Cha 14
Give or take a few points at character creation.

For skills and backgrounds, probably take Criminal, and end up with something like Stealth, Perception, Acrobatics, and Deception.

So getting into the build itself, I've plotted it out roughly level by level, and what they can do:
L1: Monk 1. Basically just punching stuff, and the level where those wood elf bonus weapons would be most handy. Attack output (with a staff and bonus attack, assuming all attacks land): 1d8+1d4+6.
I'm pretty sure staves can be used two-handed as a monk. If I'm wrong, downgrade that first die a class.
L2: Monk 2. Access to ki points and flurry of blows.
Damage output: 1d8+2d4+9.
L3: Warlock (Hexblade) 1. Hexblade's curse syngergizes really well with flurry of blows, as you're now adding +2 damage to each of those punches (1d6+2d4+15), though do to action economy, you won't be able to pop it off until round 2. For spells, take Hex and Shield. Hex can stack with Hexblades Curse to bring that flurry up to 2d4+4d6+15, if you're willing to charge up for 2 rounds. (Unless you take two bonus actions in lieu of regular actions in the same round; IE, could you cast Hex and Hexblade's curse on Round 1?)
For cantrips, probably eldritch blast or Toll the Dead and minor illusion. EB is going to be a secondary attack method at best under this build, but it's nice if you don't have longbow proficiency.
L4: Warlock 2: Two invocations, with which will probably be Devil's Sight and Mask of Many Faces. Alternatively, if you want to forgo espionage, lower your wisdom for higher con/cha, and take Armor of Shadows. You gain a 3rd 1st level spell, which I have no opinions on.
L5: Monk 3: Kensei Path, take the longbow and longsword as your Kensei Weapons. Farewell stick, hello sword. Damage output with both hexes active is 1d10+2d4+3d6+15. You also gain those funky Kensei powers which essentially give you +2 AC (most of the time) and +1d4 on ranged attacks.
L6: Warlock 3: L2 spells; if you didn't get Darkness as a racial spell at L5, you get it here, and that Darkness/Devil's Sight combo can pop off. Darkness and Hex both require concentration, so they won't stack, but Hexblade's Curse does not. Take Pact of the Blade, which will open up some good Invocations later. You can also swap out a 1st for a 2nd level spell and take Mirror Image, which does not require concentration.
Proficiency bonus goes up, bringing Doublecurse Damage up to 1d10+3d6+2d4+18.
L7: Monk 4: Finally, an ASI. +2 Dexterity, bringing Maximum Garbage Damage to 1d10+2d4+3d6+21.
L8: Monk 5. Extra attack, and unarmed strikes go up to 1d6. Damage output is up to 2d10+2d6+4d6+21. Christ.
L9: Warlock 4. Proficiency bonus goes up, and take another ASI in Dex, bringing Damage up to 2d10+2d6+4d6+29.
L10: Warlock 5. Take Eldritch Smite as your 3rd Invocation. Which following our theme of "too much damage" brings your maximum up to 2d10(base)+2d6(flurry)+4d6(hex)+4d8(smite)+29. You also get 3rd level spells here, though I've yet to develop strong opinions of those. Probably Gaseous Form and/or Fly.
L11: Monk 6. The Kensei gets Deft Strike at this point, which let's you spend another Ki point to throw another d6 onto the fire (2d10(base)+1d6(deft)+2d6(flurry)+4d6(hex)+29, by my math.

I don't have much opinion about what happens after Level 11, and in my experience, most games don't get that high in the first place.
Warlock starts hitting diminishing utility, though it might be worth taking up to L7 for 4th level spells and a 4th invocation. Or possibly dipping into Fighter for a fighting style and Action Surge, and eventually grabbing Battle Master for even more garbage you can add onto your attacks.

I think that all checks out. There's a lot of weird book-keeping in terms of what is and isn't a bonus action, what does and doesn't require concentration. Feel free to let me know if I missed anything on math or action economy, which is quite likely.

[CTurbo]

I just made a Monk/Warlock although I benefited from some really high rolled stats. I'd probably use Half-Elf if I were to make this with point buy. Dex (and maybe even Wis) is probably always going to be more important than Cha for AC purposes since you can't use armor(well you CAN, but you shouldn't).

Hexblade is probably the best patron for this still even though you should still focus on Dex over Cha. I went with fiend for story purposes.

I'm going Chain pact for story purposes although Blade probably makes more sense mechanically.

Had I gone Hexblade, I probably would have gone Long Death Monk, but since I went Fiend, I'm going Shadow. I just don't love Kensai.

I went Monk 2, and then Warlock 1 which is where I'm currently at. I will take 2 more levels of Warlock before going back to Monk for 4 more levels. At that point, I will be Monk 6/Warlock 3. I don't really intend on taking anymore Warlock levels, but if I had to stick to point buy, I could see taking one more Warlock level for ASI.

[Talionis]

In MAD builds I often suggest looking at Non Variant Human. A plus one to all Stats isn’t bad when you need four Stats decently high.