Optimizing a dual-wielding ronin blademaster

Question

We'll be starting a new campaign at level 5 in a few weeks. I I've been racking my brain over how exactly to mechanically make the most "killtastic" badass ronin character. The main problem lies in my desire to be able to kill with action, bonus action, and reaction reliably. A few things stand out to me for how to go about achieving the flavor of a master swordsman who is swift (many many many attacks), agile (dodges attacks rather than absorbing damage like a barb), cunning (doesn't rely on wearing heavy armor and using climbing equipment to solve problems), and perceptive.

The first, and honestly what I think will be most helpful, will be a Kensei monk with a katana (longsword) and wakizashi (shortsword) to start out, but quickly turning that into dual wielding longswords once I've gotten higher in levels. From Kensei 5, I plan to move to Battlemaster 3, and then either barbarian 3 for elk totem and riposte city, or swashbuckler 3 for sneak attack. BM is almost guaranteed so I can pick up riposte and parry, and Elk will fuel my ability to move around the battlefield.

How well doe these fit together in terms of:

• Most important: Consistent Damage. I don't mean stacking hex with hunter's mark or anything here, but straight base attack effectiveness. As many attacks as I can too

• Also important: Survivability

  In addition, I earned a +1 longsword in our last campaign, so that can be implemented. If you have a more effective build while still retaining the thematic ronin thing I'm going for, I'm all ears.

V Human, Pirate
STR:10 DEX:16 (15+1) CON:12 INT:10 WIS:16 (15+1) CHA:9

1. Monk, Mobile Feat
2. Monk
3. Kensei, Longsword and Longbow, Deflect missiles is a great skill
4. Monk, +2 DEX

5. Monk, Extra Attack

   STR:10 DEX:18 CON:12 INT:10 WIS:16 CHA:9

   At this point, my to hit with my main +1 longsword is +8, with a base +5 to damage, and I get a max of three attacks with weapons, although one will be a d6. I can still flurry, or use ranged weapons effectively

6-9: BM,TWF, Riposte, Parry, Either Evasive Footwork or Menacing Attack

I plan to mostly use Riposte when missed (hopefully often) in the rare times I end my turn around baddies. Alternatively, I was also thinking of switching out mobile for dual wielder around this point.

10-13: Elk Barbarian, for the sweet disadvantage I'll impose on Opportunity Attacks and resistance from raging

My real desire is to be a spinning whirlwind of doom relying on martial skill alone. Not only that, but in toe to toe martial combat, he should feel and look a great degree more skilled roll-wise than his peers. I don't know how many levels the Campaign will cover, and I don't know how available magic items will be, so I built this plan with the idea of getting online fast and not relying on much besides basic attacks.

The build needs to have many attacks, in action, bonus action, and reaction as well when possible.

It also needs to rely primarily on being hard to hit rather than high hitpoints, but also not use heavy armor or a shield.

Lastly, the build should have the flavor of a swordsman who is almost supernaturally perceptive and exceedingly agile.

Chiefly: what's the optimal class split for consistent DPR (lots of attacks, not nova and big to-hit), highest AC without heavy armor, and most mobility (movement speed) without using magic items (excepting +1 longsword)?
Assume point buy: DEX WIS and CON have priority

Answer 1

With Mobile feat at lvl 1: 6 Kensei / 3 Battle Master / Barbarian X

Most important: Consistent Damage. I don't mean stacking hex with hunter's mark or anything here, but straight base attack effectiveness. As many attacks as I can too

You can't do two weapon fighting using a longsword, nor with longsword+short sword without the dual wielder feat. Note:

Two-Weapon Fighting
When you take the Attack action and Attack with a light melee weapon that you’re holding in one hand, you can use a Bonus Action to Attack with a different light melee weapon that you’re holding in the other hand. You don’t add your ability modifier to the damage of the bonus Attack, unless that modifier is negative. (PHB, Ch 9)

If your DM is allowing you to swap feats at level 6, that's fine, but this answer is based on your stated choice of the Mobile feat at level 1. It also leverages your desire to use your +1 long sword.

At level 5, your unarmed strike is as effective as a short sword since they both do a d6. That bonus action attack does the same damage.

Starting at 5th Level, you can interfere with the flow of ki in anopponent’s body. When you hit another creature with a melee weapon Attack, you can spend 1 ki point to attempt a stunning strike. The target must succeed on a Constitution saving throw or be Stunned until the end of your next turn.

You can stun opponents to increase DPR.

With your proficiency using a long sword, you are better off for DPR purposes using it with two hands and getting d10 +4+1, d10 +4+1, d6+4 (unarmed strike) as your base damage rather d8 +4 +1, d8, d6+4. You don't have the dual wielder feat anyway (more on that later), so you can't use two long swords. The more +1 attacks you make using that +1 sword, the more often you hit. And, you want your critical hits (when they happen) rolled with a d10, not a d8 or a d6

A key thematic piece of your build: the Mobile feat. That feat is helping you avoid damage as you hit and move away. Your base movement is 50'. That's good! (+10 Monk 2, +10 Mobile).

-Your speed increases by 10 feet.
-When you use the Dash action, difficult terrain doesn’t cost you extra Movement on that turn.
-When you make a melee Attack against a creature, you don’t provoke opportunity Attacks from that creature for the rest of the turn, whether you hit or not.

Your Armor Class of 17 is telling you, at levels 5-10, move to avoid taking damage. We have found in Tier 2 play that monsters with CR 5-10 do not have that much trouble in hitting AC 17. They can't hit you if you are not there and you are avoiding opportunity attacks.
Or if they are stunned.
Or if they are dead because you got your attacks in first.

Why 6 Kensei? There are two reasons.

One with the Blade
Magic Kensei Weapons. Your attacks with your kensei Weapons count as magical for the purpose of overcoming Resistance and immunity to nonmagical attacks and damage.
Deft Strike. When you hit a target with a kensei weapon, you can spend 1 ki point to cause the weapon to deal extra damage to the target equal to your Martial Arts die. You can use this feature only once on each of your turns.

At level six reducing the capacity of foes whose resistance or immunity to reduce or negate your damage (except from that +1 sword) will be a factor. Having all three attacks always be magical matters to your DPR. You want to be always doing damage, and never allow enemies to reduce or negate damage passively. You double that deft strike die if it's on a critical hit.

At Fighter 1 (level 7) take Great weapon fighting style.

When you roll a 1 or 2 on a damage die for an Attack you make with a melee weapon that you are wielding with two hands, you can reroll the die and must use the new roll, even if the new roll is a 1 or a 2. The weapon must have the Two-Handed or Versatile property for you to gain this benefit.

Any roll of 1 or 2 on a 1d10 gets re-rolled. 8/10 of those re rolls will be an improvement in damage. DPR benefit.

BM Maneuvers at level 9:

Maneuvers: Parry, Precision Attack, Riposte.
Parry to deal with higher to-hit as your monster CR's go up when your party levels increase.
Precision Attack: meets your DPR boost objective.
Riposte: Get attacks in with a reaction, meets DPR boost objective.

Barbarian, not Rogue.

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.(Sneak Attack)

Your weapons are not finesse weapons, not light weapons, so your idea on sneak attack can't work. You'll need the damage reduction from Rage anyway as the levels go up.

Consider BM 4, not BM 3, for the Alert feat. DPR boost ....

Why? +5 to initiative and you can't be surprised.

Because you can now and again stun opponents with Stunning Strike, you can get multiple attacks on stunned opponents which gets even better if you usually attack first:

A stunned creature is incapacitated (see the condition), can’t move, and can speak only falteringly.
The creature automatically fails Strength and Dexterity Saving Throws.
Attack rolls against the creature have advantage.

They aren't attacking you. You get more chances to crit. You hit more often. More DPR.

Or, at BM 4, increase your Dexterity to 20 which:
Boosts your AC by 1
Increases DPR since you are +1 to damage on all three attacks
Means that you hit a little more often

Dual wielder feat won't help your DPR

If you want the dual wielder theme, you eat an ASI at level 4 (Dex = 16)

• and lose 1 AC,

• lose 1 to initiative

• lose one damage per hit

• Reduce your "to hit" bonus by one

Your dual wielder feat thematic idea acts in opposition to your DPR goals.

Build Order

If you take the above approach, you can build this character Monk 5, Fighter 1, Monk 6, Fighter 2, Fighter 3, Barbarian 1 ... to get the Great Weapon Fighting benefit to come on line sooner. Since you are using a +1 weapon, most of your attacks will be magical, and you may not find that delay in getting the "all attacks are magical and deft strike" to be a big enough problem.

Last thought: Items

If you can get your hands on them, Bracers of Defense and a Cloak of Displacement are two items on the "gotta have" wish list. Armor class boosts, or opponents having disadvantage on attacks, are a key piece of fulfilling your secondary goal of being survivable and agile. However, item drops are not guaranteed.