The power is already badly balanced (underpowered) and badly explained.Why not helpful? It makes more sense for Barkskin to stack with a shield than to not. Assuming it's not unbalancing, that should be the primary consideration.
A dangerous argument for adding power to the spell.If the shield bonus doesn't stack the spells is practically useless except when shapechanging. So it's only interesting for one subclass of the 2 classes with access to it.
Well, adding power is interpretable because the spell is badly explained.A dangerous argument for adding power to the spell.
It is far preferable that those two other subclasses simply do not select the spell, than making it OP for the shapechanging druid, just to make it palatable to other subclasses. Always balance a feature at its extremes.
Assuming the spell really benefits shapechanged druids much more than other druids, you would need to accompany any overall improvement with some language to the effect of "this spell acts like regular equipment in that it disappears into the shapechanging druid and cannot be taken advantage of by the caster in shifted form" etc.
Tell that to a druid with AC 16 or more, or to the one that wants to cast another spell requiring concentration, etc.As for mage armor: it would me useless for a druid as the barkskin would be better, mage armor can not be worn with armor because that would end the spell. The reason the mage armor denotes dex but also states this too "creature who isn’t wearing armor" so you can not be waering armor of any kind A shield is not armor its a shield and only increases the armor of the person so can be used with a mage armor spell as well as any thing else that's not armor you wear.
Tell that to a druid with AC 16 or more, or to the one that wants to cast another spell requiring concentration, etc.
The mage on the other hand has always a +3 bonus unless he spends one of their ability upgrades to gain a feat for armor, 8h duration and no concentration, if they are hit they don't lose the bonus and can use other spells with the concentrate tag, if the guy started with +3 dexterity he gets the same AC as with barkskin. Oh, and first level slot. In my opinion is much better the bonus a sorcerer or mage gets with this spell.
The mage starts with 10+Dex AC, casting this spell he gains a +3 bonus (13-10) and that bonus only goes away if he uses armor (or dispelled), to use armor effectively he needs a feat unless he wants disadvantages and the impossibility of casting spells. If he has +5 dex he get 18 AC, the spells grows up and stacks with dexterity. Has long duration and allows him to cast other buffs or spells with concentration. It's first level.As per mage armor: "The target’s base AC becomes 13 + its Dexterity modifier". Don't see what you are talking about a +3 bonus it does not state this at all just 13 base. Don't understand what you are talking about armor feat but the war wizard if that is what you mean is a useful and it lets you keep the concentration going even if taking damage. and barkskin as I said works under armor unlike mage armor with will not work as it is gone once you put on or wear armor over it.
D&D ' s entire combat system has been an abstraction since the beginning. I'm going to need a citation that demonstrates deflection is the only input to AC