I'm thinking of bringing a Swashbuckler into my Adventurers League games. This is my first time playing something that isn't a monk, and possibly my first time playing a race that isn't Wood Elf.
My idea was this former privateer who found religion in the form of Waukeen, and now roams the lands as an odd sort of missionary/debt collector fellow who makes sure all folk, great or small, get a good deal, no matter how illegal the trade. I'm thinking I want to bring em' up to level 9, but what sort of multiclasses would be good on a swashbuckler? Should I start as another class, and then go swashbuckler?
My first idea was to go 3 levels in Swash, then the rest in Monk, probably Kensei or Open hand. Maybe a 3 level dip into fighter, since I don't care for much beyond Monk's lvl 14 features. Another idea was for Swash/Warlock, or Swash/Paladin/Sorcerer, since CHA focus on the Swashbuckler makes this pretty good in my head.
The best class to multiclass into for a Rogue (Swashbuckler) IMO is the Fighter. I recommend at least 5 levels for Extra Attack, which if you are two-weapon fighting as per the intent of the subclass, that gives you three attacks per round to land Sneak Attack. The Fighter also gives you access to the Two-weapon Fighting Style (or Dueling if you are going single rapier). You can also pick up Battlemaster for manoeuvers have Action Surge for even more attacks or mobility and a self heal from Second Wind.
I would recommend starting Rogue for the bonus skills (Rogue then Fighter gives you 4 + background + race while Fighter then Rogue gives 3 + background + race). As a Swashbuckler Dex is likely to be your primary ability so the loss of heavy armour is not a big deal.
I'm not a fan of multiclassing Monk and Rogue. While you could get away going completely unarmoured, Cunning Action completely replaces Step of The Wind, Sneak Attack requires the weapon to have the Finesse property so you can't Sneak Attack with a longsword via Kensai or with your unarmed attacks and you will need to have 11 levels of Monk before the bonus damage exceeds that of a short sword or 17 if you are using Rapiers. If you were going for a Way of Shadows ninja I could see some benefits to a Rogue/Monk multiclass but not for a Swashbuckler.
Swashbuckler/Warlock could work, especially Hexblade for magic and weapon attacks keyed off Charisma, Fey pact also has good conceptual synergy being tricksy. Swashbuckler/Paladin/Sorcerer seems to be very busy and lacking some focus. Ultimately though, it depends on what you are trying to get out of the character.
As a follow-up. Every lvl that isn't Rogue sacrifices d3 of Sneak Attack, plus all the other good features! I say a d3, because ever 2 lvls of Rogue is 1d6 Sneak Attack.
So an multiclass away has to be worth it! Personally I think 5 lvls of Fighter is terrible for Rogue. You just lost 2.5d6 Sneak Attack damage every turn! Plus Uncanny Dodge at 5th, Evasion at 7th! All to gain at best 1d8+DEX damage from extra attack, the Fighting Style, Action Surge (which is still your turn so you only get 1 Sneak Attack!) and the Subclass.
Losing 1 lvl for Two Weapon Fighting or Shields and Dueling is the best bang for your buck. Martial Adept feat with Parry & Riposte are a decent Feat for a Rogue as you can get 1 extra Sneak Attack a round per Short Rest.
It depends on what you are trying to get out of the character. Also, it depends on the level split but Fighter can quite easily increase your damage output, although you do trade survivability for this damage.
Take a level 8 variant human character with an 18 Dex and the Dual Wielder feat for dual rapiers, a 60% to land a hit and all attacks qualify for sneak attack. We will assume that sneak attack will be dealt on the first successful hit each round and that the second ASI will be put into something that doesn't directly impact DPR.
(A) A Rogue (Swashbuckler) 8 would be making 2 attacks dealing 1d8+4 and 1d8 damage. This would give a DPR excluding sneak attack of 8.25. They have a 77.0% chance of the sneak attack being on a hit and a 7.0% chance of it being on a crit for an average of 12.74 damage. This gives a total DPR of 20.99.
(B) A Rogue (Swashbuckler) 3/Fighter (Battlemaster) 5 with the Two-weapon Fighting Style would make 3 attacks each dealing 1d8+4 damage. DPR excluding sneak attack is 15.98. They have a 85.8% chance of the sneak attack being on a hit and a 7.8% chance of it being on a crit for an average of 7.10 damage. This gives a total DPR of 23.07. This character would have Action Surge for an additional 2 attacks once per short rest (+10.65) and would have 4 superiority dice (d8) to use per short rest (+11.7) which could be spent on trip attack to grant advantage (+DPR) or use Riposte for an off turn attack (+12.80 including sneak attack and the superioty die). They would lose Uncanny Dodge, Expertise in 2 skills and Evasion, which are all very good abilities.
(C) A Rogue (Swashbuckler) 5/Fighter (Battlemaster) 3. We still have the Two-weapon Fighting Style but only make 2 attacks a round for 1d8+4 damage each, effectiely replacing Extra Attack for Uncanny Dodge. Basic DPR is 10.65, sneak attack DPR is 9.56 for a total DPR of 20.21. We also have all of the additional toys that character (B) but are limited to +5.33 from Action Surge due to fewer attacks per Attack Action.
If we increase these characters to Rogue 9 (A), Rogue 4/Fighter 5 (B) and Rogue 5/Fighter 4 (C) respectively, character (A) gains +1d6 sneak attack and the Panache ability, their total attack routine now generates a DPR of 24.18. Characters (B) and (C) do not gain an additional die of sneak attack so their basic routines stay at 23.07 and 20.21 but they also have all the additional ways of increasing their damage output.
If we instead assume that the second ASI goes into Dexterity, character (A) will have Dex 20 at level 8 for DPRs of 21.59 (L8) and 24.78 (L9). Character (B) will get Dex 20 at level 9 for DPRs of 23.07 (L8) and 24.87 (L9), with the chance to deal an additional 65.45 per short rest (Action Surge + 4x Riposte). Character (C) will also get Dex 20 at level 9 for DPRs of 20.21 (L8) and 21.41 (L9) with an additional 59.53 per short rest.
Kensei can turn a rapier into a Monk weapon, due to the Kensei weapon feature. Doesn't have to be a longsword.
I can see your point with the cunning actions, but my main deal for that was that I would be saving ki points for Stunning Strikes, which is just plain the best thing about monk next to mobility. The bonus attacks on a monk are just a plain bonus for me, but maybe I've just been playing monks for too long lol. The gist of the battle plan on that particular build was go in, hit once with a rapier as a kensei weapon, attempt to stun, then extra attack w/ unarmed strike, boost my AC, disengage freely because of swashbuckler, and use monk's speed to go to another enemy, and use martial arts to hit as a bonus action, or spend a ki point to flurry if I feel like the battle's particularly important.
But I do see your point. Swashbuckler/Warlock looked cool to me as well. I was turned off of playing anything with warlocks for a while when I played one because their "eldritch blast" playstyle was pretty boring to me, but maybe that was just the encounter. Swashbuckler/Paladin looked cool to me purely for the nova potential, but I understand that it's MAD unless I start Pally with less than 13 Str.
Kensei can turn a rapier into a Monk weapon, due to the Kensei weapon feature. Doesn't have to be a longsword.
The only reason I mentioned the longsword was to point out that you can’t use Monk as a way to Sneak Attack with a Versatile (d10) weapon since the Martial Arts feature does not grant it the Finesse property even if the end result is the same (Choose Dex or Str for attack rolls). The rapier however, does have the Finesse property and so is eligible for Sneak Attack.
If you start Rogue, select the rapier as your Kensei weapon for all the Kensei/Monk weapon benefits, if you start Monk you will need to select it as your Kensei weapon for proficiency (in addition to the Kensei/Monk weapon benefits) as well since neither Monk nor multiclassing into Rogue grant proficiency in it.
This assumes Dex 16, two weapon fighting short swords with no feats 8th lvl Rogue Expertise x4, Cunning Action, Uncanny Dodge, Evasion, ASI/Feat x2 1d6+3 Attack Action 1d6 Bonus Action 4d6 Sneak Attack
Having 2 attacks is similar to Advantage (you should get at least 1 hit a round). Which means you should get 5d6 sneak attack.
This assumes Dex 16, two weapon fighting short swords with no feats 5 Rogue/3 Fighter Expertise x2, Cunning Action, Uncanny Dodge, Second Wing, Action Surge, ASI/Feat 1d6+3 Attack Action 1d6+3 Bonus Action 3d6 Sneak Attack
You lose 1d6 from Sneak Attack, but garentee the +3 from Dex on the off-hand attack Once per Short Rest you can gain an extra Attack Action for 1 attack for 1d6+3 but Sneak Attack only applies once a turn. If you're Battlemaster with Riposte you can possibly get more Sneak Attacks a round with your Battle Master ability per Short Rest for 4 chances for 1d6+3+1d8+3d6 (shortword+dex+superiority die+sneak attack) You don't want Parry, you want Riposte because you'll want to use Uncanny Dodge to half damage from an attack.
This assumes Dex 16, two weapon fighting short swords with no feats 5 Fighter/3 Rogue Expertise x2, Cunning Action, Second Wind, Action Surge, Extra Attack, ASI/Feat 1d6+3 Attack Action 1d6+3 Extra Attack Action 1d6+3 Bonus Action 2d6 Sneak Attack
You now have 3 attacks a round each dealing 1d6+3 and once a turn 2d6 Sneak Attack Once per Short Rest you can gain an extra Attack Action for 2 more attacks for 1d6+3 each, but Sneak Attack only applies once a turn. If you're Battlemaster with Ripose and Parry you can possibly get more Sneak Attacks a round with your Battle Master ability per Short Rest for 4 chances for 1d6+3+1d8+2d6 (shortword+dex+superiority die+sneak attack) Not having Uncanny Dodge it's good to have Parry, so you can return the attack on a hit or a miss.
If every attack lands they all have roughly the same damage. Fighter has a slightly higher minimum damage. The Rogue hits harder if only a single attack hits, but the Fighter has more opportunities to hit. The Fighter has a higher "spike" damage with limited ability usage. Uncanny Dodge and Evasion can also reduce a lot of incoming damage. So they have similar damage outputs, but it's a trade of offense vs defense.
DPR factors in accuracy as well as potential damage on a hit. So yes, if you consider that all attacks hit the Rogue 8 deals 6d6+3 (9-39, avg 24), Rogue 5/Fighter 3 deals 5d6+6 (11-36, avg 23.5) and Rogue 3/Fighter 5 deals 5d6+9 (14-39, avg 26.5) (your example). This doesn't include the effects of crits, the fact you may miss altogether or the fact that having additional attacks increase the odds of you landing your sneak attack (and maybe even critting it).
What follows is a lot of maths. I've spoiler-blocked it for the benefit of those that want to skip it.
In my example a 60% chance to land a hit means that with your main hand / off hand you have a:
0.55*8.5 + 0.05*13 + 0 = 5.325 and 0.55*4.5 + 0.05*9 + 0 = 2.925 for a total of 8.25. Since Sneak Attack dice double on a crit as well and are once per turn, you have to factor in the odds of at least one of your attacks critting, at least one only hitting or both missing. I have further clarified it to only consider the result of the first successful attack, the alternative is to roll all attacks and apply sneak attack to the better result. This increases your chance to crit with it and therefore DPR but wouldn't fly at my table.
Both attacks missing is 40%*40% = 16%. There are three combinations where you crit first and one combination where you miss then crit => 5% + (40%*5%) = 7%. There are also similarly 4 combinations for hitting => 55% + (40%*55%) = 77%. The DPR from sneak attack is therefore 77% * 4d6 (14) + 7% * 8d6 (28) + 0 = 12.74.
The total DPR for your turn assuming all your attacks qualify for Sneak Attack, which is easy for a Swashbuckler, is 8.25 + 12.74 = 20.99.
The maths for characters (B) and (C) are similar. (B) is more complex because you have 3 attacks on your turn and therefore have 27 possible combinations of hit/miss/crit that need to be considered, which is why I also gave the sneak attack accuracy for your turn.
For simplicity I only considered the situation where Sneak Attack is applicable but the attacks do not have advantage since advantage may not always be available.
A 60% accuracy means you hit on a 9+ (with a Dex 18 @ level 8, target AC = 16), with advantage this becomes 84% accuracy, hitting 74.25% and critting 9.75% of the time. This means that for the level 8 character I present:
Character A: 20.99 => 27.02, odds of not hitting at least once = 2.6%
Character B: 23.07 => 30.52, odds of not hitting at least once = 0.4%
Character C: 20.21 => 26.58, odds of not hitting at least once = 2.6%
Taking your simplified example of Dex16, dual short swords, no feats with a target AC of 16 (55% accuracy) we get:
Character A: 18.03 normally and 23.72 with advantage
Character B: 18.19 normally and 24.37 with advantage
Character C: 16.64 normally and 22.35 with advantage
The results between the Rogue 8 and Rogue 3/Fighter 5 are more similar, but are still in the latter's favour.
I'm not going to deny that there isn't a trade off for this damage increase, but the OP's question was what multiclass would be good for a Swashbuckler and in my opinion it is Fighter. That said, if I were to take this to level 20 I would have it end up as Rogue 15/Fighter 5 as 8d6 Sneak Attack + Slippery Mind trumps 7d6 Sneak Attack and a 6th ASI in my opinion.
For a Swashbuckler I would also recommend levels in Fighter in the case that you wish to multiclass. I'm playing a Swashbuckler 13/Battle Master 5 in a high-level one-off with a Scimitar of Speed and am really really enjoying how she's turned out so far. Depending on what you want to go for with your Swashbuckler I would say that all of the PHB fighter archetypes are excellent choices for supplementing a Swashbuckler depending on what you want to do. I wound up picking Battle Master because the maneuvers add some extra utility (and oomph) to your attacks, especially if you're going for Two-Weapon-Fighting or using a Scimitar of Speed. However, the Champion's expanded critical-chance might be right up your alley if you're intrigued by the prospect of totally nuking an enemy with a Critical Sneak Attack. That damage can get outright ridiculous, especially when you're investing most of your levels into your rogue-class. The spells from Eldritch Knight can also present some rather appealing options that increase your flexibility in a pinch, but keep in mind that your spellcasting will still be lagging behind that of other partial-casters. Kinda wanna experiment with Swashbuckler/Eldritch Knight now that I'm thinking about it... sounds really intriguing flavor-wise at the very least.
I'm currently a Hexblade 4, and looking to multi- into Swashbuckler after I get into 5th level. She's already a criminal, and she's melee based - she uses EB only if she's out of range. Or as a last resort.
Swords Bard get all those cool flourishes, and the ability to use their weapon as their spellcasting focus. They get the rest of the Bard package, too. Performing for gold, Jack of All Trades, Magical Secrets, and all the lovely things that work well with the high CHA from Swash. Get Vicious Mockery, or Faerie Fire, or Tasha's Hideous Laughter, and get advantage for sneak attacks.