Whistle while you work: the bladesinging battlesmith.

[Quoz]

I'm working on a concept that could definitely use some refinement. Battlesmith artificer, with its ability to use int for attack and damage with any magic weapon seems like it would pair very well with bladesinger's ability to add int to AC and concentration checks. Specifically it allows for non-Finesse weapons on what is typically a Dex heavy build.

The flexibility of artificer infusions allows for a variety of weapon styles, from war hammers to thrown spears to mounted with a lance. (Casting enlarge on your steel defender gives a very sturdy and replaceable mount). While bladesinging restricts two handed use (including versatile) and shields, two weapon fighting is fine and perhaps even optimal.

Where I'm getting stuck is which of these classes should be the main and which the dip? What spells and feats should I take to compliment the build? Is the delay in spell progression and class features worth the dip?

[CheddarChampion]

I would do Bladesinger 6, Battlesmith 3, Bladesinger +X.
High Elf for 10/16/13/16/10/10
Take Int+2, Int+2, Resilient (Constitution), and Dual Wielder in that order.
This should give you good AC, good saves, good spells, good attacks/damage, mediocre HP.

Another option is Battlesmith 1, Bladesinger 6, Battlesmith+2, Bladesinger+X 8/16/14/16/10/10 for Con saves to start but I'd prefer to play the former option.

[AgenderArcee]

You're still going to need good Dex because you can only wear light armor (or use mage armor), so you'll need it for AC.

If you see this character as a martial-focused gish, I would just dip Bladesinger 2 or 3. Being higher level in Artificer gives you better infusions, Arcane Jolt, and a stronger Steel Defender. And from just two levels in Bladesinger you get the full benefits of Bladesong plus Arcane Recovery, faster spell slot progression and Wizard 1st or even 2nd level spells. Having so many spells prepared from Wizard will free up space for you to take your higher level Artificer spells while still having some 1st level utility spells. Three Wizard levels could give you access to Shadow Blade.

Personally I think dipping Battle Smith on a Bladesinger is a waste, unless it's just one level of Artificer for Con saves. You'll get Infusions that won't be better than Shadow Blade, and you'll use Int to attack when you want to be boosting Dex anyway for your AC. Not worth three whole levels of holding back your Wizard progression.

In terms of feats, Dual Wielder could be good if you want to two-weapon fight, mainly for the +1 AC. However I think it could also be worthwhile to hold an Enhanced Spell Focus in your other hand instead. You can also take Booming Blade and Green-Flame Blade cantrips from Wizard. At higher levels these will start to outpace your Extra Attack in damage.

Definitely start as Artificer for Con saves. Then wait until Artificer 5 before you take your Wizard levels, and then go back to Artificer.

[DarknessEternal]

Take Int+2, Int+2, Resilient (Constitution), and Dual Wielder in that order.

No casting while dual wielding without War Caster.

No bladesinging while dual wielding at all.

[RogueJK]

Specifically it allows for non-Finesse weapons on what is typically a Dex heavy build.

That specifically won't be much benefit. Bladesinging only works with one-handed weapons, and a Rapier does the same 1d8 damage as a Longsword or Warhammer. Plus you'll need a good DEX anyway, since Bladesinging also only works while wearing Light Armor.

No casting while dual wielding without War Caster.

No bladesinging while dual wielding at all.

The first point is true. The latter one is not.

Bladesong works with dual-wielding. You use two one-handed weapons, with one in either hand. You just can't use a two-handed weapon.

Per JC @ Sage Advice: https://twitter.com/JeremyECrawford/...98953580621824

[AgenderArcee]

No casting while dual wielding without War Caster.

No bladesinging while dual wielding at all.

You can use Bladesong while dual wielding, the restriction is that you can't use two hands to make an attack with a weapon.

[Evaar]

The first point is true. The latter one is not.

Bladesong works with dual-wielding. You use two one-handed weapons, with one in either hand. You just can't use a two-handed weapon.

Per JC @ Sage Advice: https://twitter.com/JeremyECrawford/...98953580621824

The first point isn't really true.

You can cast while dual wielding, you'll just have a hard time accessing material or somatic components. If you don't need them, then you're fine. If you DO need them, you'll need to use your free item interaction to sheathe one weapon. You can then use that same interaction next turn to draw the weapon. Use a component pouch; accessing the materials should be part of the same action used to cast the spell.

This does mean you need to structure your actions carefully, but this preserves most of the action economy. Where it will hit you is with off-turn spells like Shield.

[Garfunion]

Instead of duel wielding, pick hand crossbow and crossbow expert feat.

[Nagog]

I'd focus more on Artificer myself. With the infusion to increase AC you can focus more on Int to boost all of your martial abilities (and of course your casting) without sacrificing your HP potential. From my experience playing a Bladesinger, the AC boost is a nice touch, but fails to make the difference required to be a front-line combatant due to the utter lack of HP unless you powerbuild Con and nab Tough. Increasing your Hit Dice to a d8 will greatly help your defenses, and with a strong enough Iron Defender to impose disadvantage on your attackers, you can survive as a front-line caster tank.

[Quoz]

Thanks for the insights everyone. Looking at it again, the gains for taking bladesinger are not as high as I had been thinking. Plus by not taking an archetype that locks me into an elf can let me play with a small race so I can use my steel defender as a mount, using lance and shield for more damage, mobility, and AC. Gnome will be optimal but if rolled stats come out with a workable array I would like to give kobold a try. Style points for making the defender some type of steampunk dinosaur.

Any particular reasons why I couldn't get some barding (maybe even infused) for the defender to boost survivability? Or other good strategies at lower levels to boost tankiness? I know at level 11 I can give it the spell storing item to have it cast warding bond as an extra HP reserve.

[stoutstien]

Thanks for the insights everyone. Looking at it again, the gains for taking bladesinger are not as high as I had been thinking. Plus by not taking an archetype that locks me into an elf can let me play with a small race so I can use my steel defender as a mount, using lance and shield for more damage, mobility, and AC. Gnome will be optimal but if rolled stats come out with a workable array I would like to give kobold a try. Style points for making the defender some type of steampunk dinosaur.

Any particular reasons why I couldn't get some barding (maybe even infused) for the defender to boost survivability? Or other good strategies at lower levels to boost tankiness? I know at level 11 I can give it the spell storing item to have it cast warding bond as an extra HP reserve.

In play the BS steel defender is pretty solid even with lowish AC. Between repair and mending after combat. Later on arcane jolt can help in emergencies.
Depending on how your table plays you want the defender to no have to high of AC because you want it to draw attacks.
If planning to ride it the mounted combat feat will go a long way obviously but it really want to go all in maybe take cavalier fighter 3 for Mark and born in the saddle.

The steel defender can attune to magical items also so infusions like gauntlets of ogre or cloak of protection can add some staying power.

[Dualswinger]

There is a magic item that allows you to make a one handed melee weapon into a spellcasting focus. These items are VERY useful for Bladesingers who dual wield, and easy to build for a good Artificer (needs maybe a week of downtime)

[RogueJK]

There is a magic item that allows you to make a one handed melee weapon into a spellcasting focus. These items are VERY useful for Bladesingers who dual wield, and easy to build for a good Artificer (needs maybe a week of downtime)

Ruby of the War Mage, from Xanathar's.

[Waazraath]

If you want a wizard dip on your Battlesmith, how about Warmage? Also very nice int-synergy (+5 initiative is nice), and it's other lvl 2 feature is also very powerful depending on what you plan to do - +2 AC OR +4 to a save as a reaction (but can't cast anything but a cantrip next turn). If you run a battlesmith as weapon combatant, this is very strong. Just grab GWM or SS/CBE, and use spells mainly for utility.

[Xenken]

I would second the Warmage consideration.

[Ortho]

Have you considered dipping into Eldritch Knight instead of Bladesinger? You'll gain access to any race, heavy armor (if your first level is Fighter), a Fighting Style, and Action Surge. And Weapon Bond, though I think there's an Infusion that makes that redundant.

This is definitely more martial focused than the other options, though, since you'll be trading your away Bladesong and your spell slot progression will take a hit.