Swashbuckler Rogue/Battlemaster Fighter Multiclass

[KingWhipsy]

Hey all this is my first post and it's about my new character in a home-brewed campaign. He is a Lightfoot Halfling Swashbuckler who grew up in the church as his parents left him with the town priests when they went out on missions. They never returned from one mission and he was left to grow up in the church with the clerics son who became his "brother" (Light Cleric PC). He eventually went off to a large city and began working at a tavern before being discovered by a local pirate crew who hired him to be the front for their business. On a trip to visit back home the town was overrun by a horde of baddies who captured us and sent us to a prison camp where we met the rest of the party and here we are.

The main questions I have are about multi-classing as I think going into battle-master would be super beneficial to my character in his backstory and also for combat reasons. Our party consists of 6 level 4 PCs. Halfling Swashbuckler (me), Light Cleric, Champion Fighter, Phoenix Sorcerer, Arcane Archer Fighter, and Circle of the Moon Druid. We just hit level 4 and I think it's pretty much a given i'm putting 2 in DEX to put me at 20. My stats are here: (STR 11, DEX 20, CON 14, INT 13, WIS 13, CHA 16). I'm just wondering when it's best to multiclass into fighter and how many levels to take when I do decide to dip. I was thinking now that I got 20 DEX it'd be a good time and going 5 or 6 levels into fighter now for either extra attack or extra attack and an ASI. After 6 going back into rogue until 12 and finishing the last 2 levels into fighter. I also have studded leather armor so I have a respectable 17 AC and before the campaign started we all got a magical item mine is a Sentient +1 Rapier that grants 2 superiority die and the Riposte and Parry maneuvers; in addition it grants me one failed Charisma check without repercussions per long rest.

The build that I have thought out gives me 6 more ASI's and i'm wondering what feats or skill increases I should pursue. Dual-Wielder seems like a given so that I can increase the offhand damage and my AC while also fitting in more with the idea I have of the character. Magic Initiate is interesting as it grants additional damage and some utility. Alert would make me have near unbeatable Initiative. Lucky seems almost too good not to take as well. I've been perusing homebrewed feats as well looking for interesting things I could propose to my DM, so if you have any of these that'd be awesome too.

In going into Fighter i'm also torn between Mariner and Two Weapon Fighting as the bonus AC from mariner is nice and it fits extremely thematically with the character, but +5 damage to my offhand attack from TWF seems almost too good to pass up. Overall i'm looking at when to go into fighter and how many levels before going back into rogue, as well as what I should do at my ASI's as there are lots of options that seem interesting. If trying to min-max as hard as possible when would be the appropriate times to do each of these things?

Thanks for taking the time to get this far and I look forward to your responses!

[bid]

In going into Fighter i'm also torn between Mariner and Two Weapon Fighting as the bonus AC from mariner is nice and it fits extremely thematically with the character, but +5 damage to my offhand attack from TWF seems almost too good to pass up.
Your SA wants 2 chances to hit, fighter 5 will give you that. Once you reach that point, you might want shield master and expertise in athletics. Think which way your RP concept takes you before picking those.

The main pull of DW is whip and its reach, more than the extra 1 damage per attack from the bigger dice.

You absolutely need riposte, it's the best way to get a second SA in the same round.

Fighter 6 vs rogue 15: you are trading the equivalent of resilient(Wis) + 1d6 SA for an early feat. Sometimes getting it now is better than at the never-reached level 20.
The next good "damage" split is fighter 11 / rogue 9. I don't think BM 7 or an extra feat beats rogue 13-14.

[Nidgit]

Uncanny Dodge and another d6 of Sneak Attack is probably good enough to warrant going to Level 5 in Rogue first, but then you've got the right idea of switching to Fighter for 5-6 levels. After that it's just a matter of what balance you want, though going at least Rogue 7 for Evasion is probably smart.

As for the rest of your questions, I'd tend to favor Mariner over TWF since Rogue gives you a lot of competition for your Bonus Action, though Swashbuckler does make it more viable. Alert is neat but you don't really need it if you're not an Assassin. Magic Initiate can be fantastic, especially if you use BB to augment your Sneak Attacks (don't need as any Fighter levels then either). Sentinel is also another useful option, particularly for more melee-ready Shawshbucklers, as it's another opportunity for a Sneak Attack.

[pdegan2814]

As a Swashbuckler I would go with TWF, their ability to step away from people they attack without needing to Disengage means more Bonus Actions available for the off-hand attack, which gives you extra chances for Sneak Attack. Along those lines, if you go BattleMaster then Precision Attack is a must, so those near-misses can become hits. Champion is also a legit choice since more frequent crits goes well with Sneak Attack :)

[djreynolds]

I would take this build to 7th and then multiclass. Grab evasion and 2 more skills with expertise

Then grab a level of fighter or even ranger, as you have the stats.

And when you find a feat you want then grab that 8th level of rogue.