The Steel Juggernaut Build

[Melphizard]

So I'm looking to get this build idea out there and to see if I could get any outside opinions on cool multiclass options or varying stratagems I could incorporate into this idea. Any advice would be much appreciated. I also may get some stuff wrong so apologies if I do. This is for adventurer's league play.

Concept: I'm playing a level 16 character with the primary goal of having one big summon and thus have decided my best course of action is to make a Battlesmith and use every infusion possible to turn my Steel Defender into a Steel Juggernaut

Rules:
1. I have access to the core books of: PHB, SCAG, XTG, TCoE, DMG, EE, and VGtM. Custom race from Tasha's is allowed, so is shifting up the stats.
2. I have access to 1 rare and 2 uncommon magical items (common magic items also are fine within reason). >> Note that this is watered down and I'm a long time AL player who has DM'd and played a lot so I have access to quite the number of items <<
3. With whatever shenanigans be it magic item exploitation, rules lawyer, and/or multiclassing I want my Steel Defender to functionally be a functional and strong ally for my party.
4. My Steel Defender shall be my main summon and will be what I primarily rely on, not other summons that could possibly be included.


Example of my current build concept:
Battlesmith 15, Peace Cleric 1
Race: Fire Genasi
Base Stats:
Str: 8 Dex: 12 Con: 16 (14+2) Int 16 (15+1) Wis: 13 Cha: 10
Future Stats: Feats - Resilient Wisdom

Str: 8 Dex: 12 Con 16 Int: 20 Wis: 14 Cha: 10

Magical items: (R) Periapt of Proof Against Poison, (U) Broom of Flying, (U) [A] +1 All-Purpose Tool

Infusions used (all for my defender): [A] Belt of Hill Giant Str, [A] Bracer's of Defense, [A] Cloak of the Bat, [A] Headband of Intellect, Goggles of the Night

Tactic: Before a fight or when we enter a dangerous area, I active Emboldening Bond on my Steel Defender, then casting Warding Bond with a 2nd level spell slot, then follow it up with Longstider cast from my spell storing staff, granted to everyone in the party.
Combat round 1: Cast haste upon my defender then use my bonus action to send them out into the battle.
Combat round 2: To protect the haste I cast blink upon myself and then follow up with a bonus action to send my defender out after someone
Combat round 3: Simply begin blasting, reserving your bonus action on all turns for your defender.

Ofc, this could be improved, so I'm interested to hear other's thoughts on this concept.

[Dork_Forge]

I'm going to bed so will contribute to this more thoroughly tomorrow but some off the cuff thoughts:

-You should be taking advantage of Aid to bolster both the SD and the party's HP

-I see no point in giving the SD an item like a Headband of Intellect, it's eating an infusion and attunement slot that could be better served elsewhere

-If rare is on the table and you can pick your items (or just have so many that it's basically picking them) then Ring of Spell Storing for the SD loaded up with castings of Shield and Absorb Elements would be good. For safety's sake I'd also include a single casting of 1st level Cure Wounds, giving the SD the ability to pick someone back up if need be, as by their very design they should be one of the last PC side creatures standing.

[kore]

While apropos for the class, I think you might be over-engineering this build.

Obviously, if the RP is that you are some meek (or otherwise non-threatening) inventor who has created a walking tank to take on your enemies then much of my criticism doesn't apply because it's ultimately your vision. But what I'm seeing is a lot of inefficiencies and lost opportunities with the route you've chosen.

There are some other missing pieces to this build like your feat/ASI choices and some of my suggestions may or may not line up with your choices. And this is where my first suggestion starts, and it addresses the inefficiency of MC'ing into Peace Cleric. While a level dip into Peace Domain basically gets you slot-less Bless of sorts, I'd recommend doing a custom lineage for your Fire Genasi and take the Fey Touched feat at L1 to pick up Bless. You could then either feed this into a Ring of Spell Storing (as your Rare magic item choice) or cast it from your slots.

Something that is not clear is what role your Steel Defender plays in the party and how it accomplishes that role. It seems like you're putting most of your resources into it but I think the return on such an investment will be poor. I realize that this choice may be for RP purposes but I'm merely pointing out all that you're giving up. First, I question whether casting Haste on your SD will allow you give a command with your Bonus Action for both actions. And whether it could just take the Dodge action with its extra action is questionable. But those things aside, what is your SD contributing with an extra action that wouldn't be better served by an ally (or yourself) getting Haste?

- Cloak of the Bat: what's the purpose of providing conditional flight and limited Polymorph to the SD? Why not give it Winged Boots? And then again, why not give Winged Boots to an ally (or yourself)?
- Goggles of Night: again, why? The SD has darkvision from the outset.
- STR, INT, and AC boosting Infusions: is this strictly boosting defense? The Headband of Intellect is an inspired choice and I'm not strictly against putting an Infusion on the SD. In fact, I might consider swapping Enhanced Defense out on my SD for a HoI. But to put all of these into the SD seems like a waste. Don't forget, you have Flash of Genius for those critical moments when someone needs a boost to a saving throw.

I suppose what it comes down to is what makes your SD a threat such that it's a better target than you or your allies? If you made the HoI into your SSI with Bless stored so that your SD is casting/concentrating (as a Bonus Action no less) on it then it would be quite threatening; putting Mind Sharpener on the SD might be a good alternative here. But it's damage output will never be something that diverts attacks from you or your allies. Another suggestion is to turn it into a HP sink: put Warding Bond into the SSI with your SD and have it cast it on you. You now have a +1 AC and saving throws, resistance, and the HP your SD loses can be "healed" out-of-combat via Mending. Make your character the threat but tough-to-crack while the SD is around. You then keep the SD close for its reaction and have it Dodge, now it's a multifunctional shield generator. And if things get too close for comfort, have it back off the frontline, cast Sanctuary on it, and/or expend an Arcane Jolt on it.

For a Battle Smith it's difficult to find a good level to MC and I think L16 is the first place I would consider it but I'd probably look at going Wizard and then War Magic. But even then you're delaying an ASI/feat. At L15 I'd be at Fey Touched, CBE, SS, and +2 INT so L16 would look ripe for another +2 INT or War Caster.

tl;dr
- Reduce the number of Infusions on the SD, it's a waste.
- Find a way to make your SD threatening.
- Avoid MC and get Bless via Fey Touched.