Is gaining 1 AC in exchange for disadvantage on Perception checks a balanced trade?

Question

Inspired by this answer, and to avoid lengthy back and forth comments, I decided to make this a question in itself.

You can put on your helmet for +1 AC and disadvantage on Perception checks. In combat, this'll likely mean -5 to your passive Perception.

I believe that this is a pretty amazing trade. You are becoming a lot more difficult to hit because of bounded accuracy, and trading this for a minuscule chance that some enemy will be able to hide better from you to gain advantage.

Note that this is not, mathematically, the same as trading +1 AC for giving enemies advantage. As they will have to first take the Hide action to even be hidden to get that advantage, they're essentially sacrificing attacking twice to gain advantage (unless they're a rogue of sorts).

Is gaining +1 AC in combat by gaining disadvantage on Perception checks a balanced trade?

Note: I am working under the assumption that you will simply take your helmet off again after the fight, so you are not walking into traps or ambushes with disadvantage. You are putting on your helmet as your free object interaction in the first turn. The penalty only comes into effect during combat, as does the +1 AC.

Answer 1

It is a very strong trade, combat-wise, as a free object interaction.

If you are exploring a dungeon, and have your weapons drawn, and helmet off, you minimize your risk of being surprised and use your object interaction to put the helmet on (assuming your DM lets you do so). If enemies are tricksters that rely on being hidden, you can choose not to put the helmet on, or remove it during combat.

The helmet might not be so useful on surprise combat in non-combat areas. If you don't have your weapons drawn, you need 2 turns to put the helmet on: on the first turn, draw weapon. On the 2nd, put the helmet on. 3 turns if you're a 2-weapon fighter.

That being said, armor usually takes more to be donned than 1 free object interaction. A shield takes an action, and heavy armor takes up to 10 minutes. Your DM may (like I would) classify the helmet as armor (since it gives you 1AC, and, flavor-wise, needs to be well adjusted on your head in order to be effective), and rule that a free object interaction is not enough to don it. When considering how balanced this is (or not), it has to depend on the rarity of the item that attributes it.

Answer 2

This is not balanced

The concern with this is that many characters who wear armor are on the front-line. Their job isn't to be perceptive, their job is to smash and stay alive. Trading away some perception for increased survivability becomes a no-brainer. And anything that's a "definitely yes" decision tree is unlikely to be balanced.

AC vs Perception

Whether or not skill checks are used in combat is going to be very DM dependent. Looking at this from a purely mechanical perspective, AC is always on. Skill checks are dependent upon the DM and on the table. Player roles also start to become involved. If someone has built a character for combat and is willing to let softer skills suffer (not an uncommon decision), then this becomes a very clear decision. Especially if other party members pick up the slack on the skills side.

But if your table utilizes perception and other skills more frequently, and more specifically in combat, then the trade-off becomes more interesting as they'll have to decide if it's 'worth it'. But at that point, as other answers have suggested, moving this to an action cost for don/doffing also becomes necessary.

Equivalence/relationship to existing magical items

+1 Armor

This is basically an option to turn on/off a +1 to armor. +1 armor is itself a rare item, so if you were to offer this, it should be treated like a rare magic item, but providing a cost for donning/doffing should also be a consideration. However, it's important to note that you can wear this and have it stack with the armor, which increases it's value/rarity when doing so.

Bracers of Defense

The Bracers provide a +2 AC, but have the limitation of no armor or shield being used. It's a standalone item that can't be combined with armor, but is still rated as Rare.

Answer 3

YMMV

Ultimately it depends on what kind of game you are playing.

If you play a campaign that is essentially a hack 'n' slash meatgrinder where enemies move forward and attack, then having disadvantage on perception is no problem at all--you may never even roll perception the entire dungeon. You can also capitalize on the AC bonus by easily soaking up all the attacks from the mindless enemies.

However, if you are playing a more classic style game with tactics, traps, hazards, and enemies that may be drawn to the fight, then having disadvantage on perception is huge--you may be required to make perception checks multiple times per fight. What's more, the +1 AC may not really matter in this kind of game. Why use attacks against the tanky guy with the fancy hat? Attack the squish caster, use spells on the high AC tank!

And then there's the action economy...

Having one more item that needs to be donned and doffed during combat and takes up space in your hand or has to be stored on your body can cause you a lot of problems.

Again, if it's just a meat grinder, it doesn't matter.

But if you are playing a more roleplaying playstyle, then you probably want to have your hat off so you can use your perception. You may have a torch, you may have your shield in one hand, maybe you want to have a weapon at the ready, you may need a free hand for touching things.

Suddenly you don't have enough hands for everything, you need to prioritise. Assuming you have 1 hand free and 1 hand with a torch, on your first turn you probably want to retrieve your helm with free object interaction, and don it with your action. That's a whole turn used up. Next turn you can draw your weapon. Losing a whole turn of actions is a big disadvantage that shouldn't be underestimated. Similarly if you do need to Search then you need to doff your helm, which of course you need a free hand for...

Answer 4

It would not balance out unless donning and doffing the helmet was a full action.

In order for the trade to be balanced, the amount of positive should be equal, or near equal, to the negative. In this case, wearing a helmet gives a better armor class (positive) but gives disadvantage to perception checks (negative).

But you're also saying that donning the helmet is a free action. Which means the player will spend 99% of the time with it off (no negative) and only put it on at the start of combat with no penalty. So the only time the disadvantage would occur is during actual combat. I could count on one hand the number of times I needed a player to make a passive perception check during combat. But there aren't enough fingers and toes to count when +1 AC would have saved someone's bacon.

In order to balance it out, you need to make donning and doffing the helmet the same as donning and doffing a shield; 1 Action. Now the player must choose between always wearing the helmet so they are ready to go, or generally keeping it off to better see but losing a round of combat to increase their AC.