Help with my Halfling Yakuza build

[Coec]

My apologies up front on the long post.

I'm new to 5e dnd, though I have played 3.5 and pathfinder so I'm somewhat familiar with character creation. I recently joined a gaming group in my area and started down path of becoming a Lightroom halfling rogue. I'm currently level 3 and chose assassin as my archetype.

Stats: str 13, dex 17, con 10, int 10, wis 12, cha 14 (27 point buy).

Chosen skills: acrobatics, deception, stealth, perception, sleight of hands, and persuasion.

I took stealth and thieves tools as my first set of expertise and was thinking of deception and perception at rogue level 6th expertise.

I'm looking at going Assassin rogue (12-13), Raven Queen Warlock (2-5), Samurai fighter (2-6).

The warlock invocations I would take would be devil's sight and armor of shadows. I chose samurai primarily for the fighting spirit ability and the concept idea.

What I'm looking for is help in how best to optimize when i get my asi/feats based on how I want to multiclass.

My original plan is:
1-4. Rogue: feat lucky
5. Warlock
6. Warlock: get my invocations
7-13. Rogue: feat dual wield @10, asi dex +2 @12
14-20. No clue how best to finish.

I'm flexible on the order and when to multiclass with the exception to the first 3 levels as i am already level 3. Also I'm looking for any good suggestions for feats beyond lucky and dual wield. And if you made it this far I greatly appreciate your time.

Thanks

[Quoz]

Dual wield may be a bit of a trap option. Not terrible, but there are probably better. Any bump to your dex modifier will give you about the same bonuses and then some (+1 AC, attack, damage, initiative, dex save, and several skills vs +1 AC and bumping up your weapon from d6 to d8). Rogues have a lot of options for bonus actions, dual wielding is often not the best choice.

Perhaps a better option would be to snag a level of fighter or hexblade warlock for shield proficiency and get shield master. Take Athletics as one of your expertise options at rogue 6 and you can be shoving opponents prone for your bonus action all day, setting up your sneak attack and guaranteeing advantage.

If you go fighter, look at battlemaster. They get a lot of options for a tough guy fighter - trips, disarms, intimidation. And it is a rider on a successful attack so no wasted actions.

When you get warlock, make sure to get either booming blade or greenflame blade. They are cantrip spells that augment a melee attack. Both will be a pure damage increase for your build with little drawback.

[Crgaston]

Looks like a fun build!
Quoz gives good advice.

I’d split that first ASI between Str and Dex to bump the bonuses to +2 and +4, respectively. A Dex of 19 won’t give you any benefit over an 18.

Also, if you’re married to using 2 melee weapons, couple levels of Fighter early will get you a fighting style and Action Surge. As far as fighting styles go, your choices are Archery for the +2 to hit, Defense for the +1 AC, or TWF.

TWF will be more beneficial than Dual wielding since it lets you apply your Dex to your second weapon’s damage, especially since you could use the ASI to bump your Dex instead. And you want your Dex at 20 ASAP.

Other feat options would be Alert, since your assassin abilities benefit from having high initiative. Also, Mobile can replace your Cunning (bonus) action Disengage for hit and run tactics while using 2 weapons.

Three classes is a lot to balance, but the overall flavor is nice. Getting them all represented quickly will probably let you enjoy your concept longer, so something like:
Rogue 4-6
Warlock 2
Fighter 1-2
as a baseline, then fleshing out from there depending on if you want more spells or more skill at arms.

Good luck, and have fun!

[Coec]

Thanks for the input. I've definitely got a lot to figure out and you've given me some excellent advice on how to proceed.