Quote Originally Posted by JackPhoenix View Post
No, it needs to be more tightly linked with a class. Taking a level of cleric shouldn't allow you to cast wizard spells in armor.
How do you do that? "You can only cast spells while wearing armor that are from the same class that provided the proficiency"? And then you have to come up with some artificial reason why Wizard spells don't work if you're wearing leather armor, but the same spell when cast by an Artificer does. (Or even more glaringly, if you're an Artificer/Wizard multiclass, why the spells coming out of your Wizard spellbook require you to strip down to your skivvies, but the spells in your Artificer formula book don't.)

I think divorcing armor casting from class is the easier route - at least, less confusing. Make it a feat; everyone is getting one at 1st level now anyway. If 'Armored Caster' is a level 1 only feat, then Clerics can grab it, and MCing into Cleric won't allow it. Feat tax? Maybe. But if there are other level 1 only feats that actually compete with it so it's a true choice and not a must have, it'd work.