Okay, I'm super confused about stacking mechanics in EOB series.

So there are different kinds of armor including Armor, Bracers, Shields, Helmets. There are also Rings of Protection.

Any kind of armor or accessory can have a magical defense bonus.

I believe from doing some searching that the Rings of Protection bonuses DO NOT stack with any magical bonus that Body Armor has.

I'm not 100% sure about that, but it seems to be the case.

What I still don't know is if magical bonuses from other accessories will stack with the armor's magical bonus or the rings magical bonus, or with each other.

For example, if I have Plate Mail +2, Ring of Protection +2, Bracers +2, Shield+2, what's the best combo I can make out of this assortment, and what bonuses cancel other bonuses, or is it all of them (I can wear all four things, but will only receive a single item bonus.

Thanks

As far as I know, in 2e rules (which is what the EotB series use), you can only use one 'Protection' type of item, and the protection is canceled when you're wearing magical armour.
So if you have a ring of protection, cloak of protection, bracers of protection, and whatnot, the item with the highest protection value is used, unless you're wearing magical armour; then none of them work.

One thing to keep in mind: these protection items give a plus to armour class, but also a plus to saving throws.
Some have stated that the plus to saving throws does work in combination with magic armour, but I have no clue how you'd verify this, especially in this game.

Anyone feel absolutely free to correct me. My knowledge is limited and might be flawed.

I went to the RPG stack exchange and asked about 2e stacking rules with Magical Armor, and apparently all armor bonuses stack, but magical items (ring and bracers) do not stack with the armor. So if you have a magical shield and armor, those do stack, but the ring won't also work, and the bracers only work if you aren't wearing armor. The definition of armor is somewhat loose in 2e though, and people generally believe that even a defensive item like a shield is also "armor," but I don't. Also, the rules for bracers say that you have to be wearing armor to lose the bonus, and a shield isn't worn, it's held.

It's just the magical accessories that don't stack with armor. Magical Armor stacks with other Magical defense items. Basically that mean you can have a magical shield and magical armor, and they stack, but they can't stack with a ring of protection, so that makes sense. If you had a magical helmet, it would stack too, but magical helms do not appear in the OG 2e rules. Not sure if they made it into say, BG 1 or 2, it's been way too long since I played those games to remember. I still think they cover a part of your body that a shield wouldn't always be covering, depending on what's going on. The numbers are there to show you have a statistical advantage (or not) of deflecting damage, and having both things definitely covers up more of your body. I think it's correct that you can have bracers and a shield. 100%

It's also not really unfair considering that classes that can't wear shields can't get any bonus from it anyways.