It depends on the DM whether it’s particularly broken, but RAW, anything considered a ‘Creature’ can attune to/use magic items, with 3 attunement slots. In the DMG it even mentions that monsters with spell slots who use a specific spell list, can attune to items with a certain class prerequisite. The Steel Defender is considered a creature, as well as animal companions and familiars, so by the rules you’re good to go!
As for feats, since only under specific circumstances do spells that affect a player also affect their familiar (or similar creature), I think that feats are a special case, where 1: it depends on the feat; a companion with Magic Initiate would be over powered; but one with Martial Adept, while possibly over powered, could also provide very interesting combat opportunities. And 2: if the feat is scaled down or otherwise balanced in some way. Also if the DM allows it of course. And there are always ways to balance against extra powerful players too.
Doesn't sound horribly out of balance to me, though note that anything that uses the owner's ability (such as force-empowered rend on a steel defender) won't benefit.
I think the variant rules on sidekicks in Tasha's could be very helpful here.
This would allow them to improve with the party, gives you options for features, and like said above, a nice chassis to attach items or attunement slots to
I don’t think any feat with spell casting would work. Animals can’t use verbal components. I’m not sure if the steel defender would speak either.
The feat I am thinking about that might push the limits would be sentinel. It would be useful for a ranged combatant to have their companion lock down their target from moving. But as soon as you have multiple enemies it’s not that big of an advantage.
I have to check on Ranger companions, I can’t remember if they get their own reaction. The steel defender does as it’s designed to impose disadvantage on attacks with a reaction.
How broken would it be to allow someone to upgrade their companion with magic items & feats?
By companion I mean the Battle Smith Artificer’s steel defender, or a Ranger’s animal companion.
By upgrade I mean when a character can take a feat, they do so but that feat applies to the companion only.
And magic items being allowed to attune to the companion up to the standard 3 limit.
It depends on the DM whether it’s particularly broken, but RAW, anything considered a ‘Creature’ can attune to/use magic items, with 3 attunement slots. In the DMG it even mentions that monsters with spell slots who use a specific spell list, can attune to items with a certain class prerequisite. The Steel Defender is considered a creature, as well as animal companions and familiars, so by the rules you’re good to go!
As for feats, since only under specific circumstances do spells that affect a player also affect their familiar (or similar creature), I think that feats are a special case, where 1: it depends on the feat; a companion with Magic Initiate would be over powered; but one with Martial Adept, while possibly over powered, could also provide very interesting combat opportunities. And 2: if the feat is scaled down or otherwise balanced in some way. Also if the DM allows it of course. And there are always ways to balance against extra powerful players too.
:)
Doesn't sound horribly out of balance to me, though note that anything that uses the owner's ability (such as force-empowered rend on a steel defender) won't benefit.
I think the variant rules on sidekicks in Tasha's could be very helpful here.
This would allow them to improve with the party, gives you options for features, and like said above, a nice chassis to attach items or attunement slots to
I don’t think any feat with spell casting would work. Animals can’t use verbal components. I’m not sure if the steel defender would speak either.
The feat I am thinking about that might push the limits would be sentinel. It would be useful for a ranged combatant to have their companion lock down their target from moving. But as soon as you have multiple enemies it’s not that big of an advantage.
I have to check on Ranger companions, I can’t remember if they get their own reaction. The steel defender does as it’s designed to impose disadvantage on attacks with a reaction.
I'd be careful with Steel Defender. The Battle Smith already gets extra attunement slots, adding another 3 is a bit bonkers.
Allowing one attunement slot might be a good start. See how that plays out before you bump them up to full PC status.
My homebrew subclasses (full list here)
(Artificer) Swordmage | Glasswright | (Barbarian) Path of the Savage Embrace
(Bard) College of Dance | (Fighter) Warlord | Cannoneer
(Monk) Way of the Elements | (Ranger) Blade Dancer
(Rogue) DaggerMaster | Inquisitor | (Sorcerer) Riftwalker | Spellfist
(Warlock) The Swarm