Can't Touch This! (Monk/Warlock Multiclass Build)
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This build is meant to have fantastic crowd control, using eldritch blast as an opportunity attack to move targets around the field on a whim.
Before you bring this build to the table, make sure your DM will let you use the homebrew monk subclass Way of the Cobalt Soul. This is balanced and most DM’s will allow it since it’s by WOTC affiliated DM Matt Mercer, but it is still technically homebrew. To get around this, you could take 18 levels of fighter 2 warlock, but you lose out on some of your invocations.
For your race you'll want Variant Human so you can take the Polearm Master Feat.
For our first twelve levels, we take Monk levels. Specifically, Monk: Way of the Cobalt Soul. We are taking this for the additional reactions and we need the ASI's.
Now we need to take eight levels of warlock. This is required for the following reasons: 1. We need eldritch blast. 2. We need the invocations "Repelling Blast", “Grasp of Hadar”, “Lance of Lethargy” and "Agonizing Blast". 3. We need the "War Caster" feat. 4. We need to increase our charisma
You need to max out your Intelligence first and then later get Charisma up to 20. If you're using the Standard Array (I never use it but some people do.) you should put your 15 in Int and your 14 in Cha. Your other stats don't matter at all. If you’re using point buy, put 15’s in both Cha and Int.
Variant Human, Monk 1, take the "Sentinel" Feat. Put your two points from variant human into Intelligence and Charisma.
Monk 3. Way of the Cobalt Soul.
Monk 4. Take the "Polearm Master" feat.
Monk 8. Increase your intelligence.
Monk 11. We now gain additional reactions equal to our intelligence modifier.
Monk 12. This is our last monk level and we'll take the ASI for our Charisma Score.
Warlock 1. Now we move over to warlock. Your pact doesn't matter, just take whatever fits your character the most. Your spells don’t matter either, but make sure you score the “Eldritch Blast” cantrip.
Warlock 2. You’ll want to take the invocations "Repelling Blast" and “Grasp of Hadar”
Warlock 3. The pact boon that you take doesn’t matter.
Warlock 4. Take the “War Caster” feat.
Warlock 5. Take the “Lance of Lethargy” invocation.
Warlock 7. Take the “Agonizing Blast” invocation. (Note: the order that you take the four necessary invocations is pretty much up to you.)
Warlock 8. Our capstone for this build is an ASI that we’ll use to increase our Charisma modifier. If you used Point Buy or rolled for your stats, hopefully you can max it out. If you used the Standard Array then you should only increase your Charisma to 18 and put your last point into something else.
Why did I do all of that?
Well, you can now cast eldritch blast if someone comes near you, meaning you can push people away from you and make them slower because of your invocations. You can do this up to six times per round, meaning you are effectively untouchable. You can also pull targets toward you if they attempt to retreat, and the disengage action doesn’t work against you.