Fiendish Vigor is a fine choice, but it's mostly a placeholder until next level. Having both proficiency and advantage on concentration checks is a big deal for a front line caster and it saves us a feat by making War Caster mostly redundant. Warlock 2: For our invocations, we take Eldritch Mind and Fiendish Vigor.Hex is a solid damage buff that gives us something to do with our bonus action, and PfEG is situationally awesome so we take it for when we need it For our spells we take Hex and Protection from Evil and Good. It's not particularly great yet, but it will be in 2 more levels. Warlock 1: We go Celestial for the healing it provides.Fighter 5: Extra Attack, switch to the Dueling fighting style if you went Defense at 1.

Fighter 4: Elven Accuracy for x3 advantage and an 18 DEX score.These are what I would prefer for this build but Menacing Attack, Parry, and Precision Attack are great maneuvers also Fighter 3: Take BM for your subclass and Feinting Attack, Tripping Attack, and Riposte for your maneuvers.Fighter 1: Go sword and shield for your weapons and Defense for your fighting style if your DM plays with Martial Versatility, if not take Dueling instead.This'll give us some more bonus action healing and max out our rolls on it, second wind, and short rest hit die to make us more resilient throughout the adventuring day For this build though, I'm going to go with Celestial as my patron because we won't be needing Pact of the Blade, so we'll go Pact of the Chain and take Gift of the Ever Living Ones. We don't have a lot to do with our bonus action outside of cast Shadow Blade so Warlock subclasses that give you one are a good choice. Other notable choices though are Echo Knight and SamuraiĪnd as far as Warlock subclasses go, you can pretty much go whatever you want. Now this multiclass can work with other Fighter subclasses, but I chose Battle Master because Shadow Blade works with Elven Accuracy and they're probably the best subclass overall for granting themselves advantage. The progression isn't even that bad as you're just a regular Battle Master till 5 and the 1st and 2nd levels of Warlock are notoriously front-loaded so you're getting a lot of mileage out of them compared to the fighter's 6-7 features and then the build fully comes online at 8 When compared to an EK, Battle Master 5/Warlock 9 is getting the spell one level later, but getting three times as many spell slots to cast it with and much quicker scaling on the damage While I wouldn't say it's better than a BS, the idea behind this build is that an EK's spell slot progression is so slow that you can choose a different fighter subclass with better features and multiclass into Warlock to achieve greater results When people bring up Shadow Blade, they always talk about Bladesinger (BS) or Eldritch Knight (EK), and to a less extent Arcane Tricksters but that's less for the damage and more for the advantage it grants, but multiclassing warlock with a martial character is never mentioned.

Shadow blade bladesinger