How to know if an equipment item will be imbalancing at a given PC level?

Question

This comment from another question has me worried:

I am curious if you had a specific reason for allowing the player to find a +2 Shield given their level.

This has me worried because I just allowed a player's level 2 Ranger to purchase a wooden shield (+2 AC) from the PHB's equipment list.

It seemed reasonable at the time: the PC was talking to an armorsmith in his shop and had enough money to pay the listed cost for a shield. To me, a novice GM, +2 AC didn't seem game-breaking at all, however the linked question has highlighted that accidentally giving players potentially unbalanacing items is a possibility.

The shield hasn't been too much of an issue so far, but I am worried I could make similar mistakes which could be more difficult to fix. I've not had any specific problems as of yet, but it seems like I could quite easily give them what I perceive to be "a standard piece of equipment" again but it turns out to be A Big Deal.

Given my lack of experience with RPGs and as a DM, how can I tell ahead of time whether an item is considered "overpowered" for a particular PC level, or may cause difficulties for me further down the line?

It seems that there are enough questions about GMs being concerned about overly powerful PCs^{[1],[2],[3],[4]} to warrant this question. The fact that questions exist like "abnormally high AC" is worrying and makes me unsure about what I don't know about equipment and balance.

Answer 1

Tables in the DMG can help

As you say, there's no substitute for knowing the power of magic items in any given system. Indeed, even the DMG itself has some wonky valuations on some of its magic items.

That being said, there are several tables in the DMG that I often refer to to get a sense of the power of specific magic items.

The first is on DMG 38, which describes the starting equipment for PCs at different levels. That table should show you what the designers considered to be appropriate magic item loadouts for characters at those levels. This table is mostly useful for knowing how many magic items a PC should have, though you should keep in mind that those are only starting values, and characters are expected to get more magic items throughout a campaign.

The second is on DMG 135, which compares the rarities of magic items to character levels. This is useful for knowing how powerful a magic item should be, and at what level characters should be getting those items. You can combine this with the table on DMG 285, which compares the rarities of magic items to the spell level of the spells they recreate.

Not every magic item duplicates a spell effect, however. There's not much help on determining what the rarity of a magic item should be--the only way to know that is to read through the existing magic item list to get a sense of how strong an item should be at a particular rarity.

An example

According to the DMG, a +2 shield is rare. Using the Magic Item Rarity table on DMG 135, we can see that it's appropriate for a character of level 5 or higher. Looking at the table on DMG 38, in the "High Magic Campaign" section, we see that characters starting at levels 5-10 don't have any rare magic items, but characters starting at levels 11-16 have one. This suggests that the +2 shield should probably be the only rare magic item that a character should have, at least until much higher levels.

Note that a +2 shield gives a total of +4 to AC, because ordinary nonmagical shields give +2 to AC by themselves. The nomenclature is such that any modifications (+1, +2) are magic modifications beyond the mundane properties of that item. Therefore, it looks like the shield you gave to that rogue is just a mundane shield, which is balanced by other mechanics (can't use a bow, can't use two handed weapons, etc.).

Being OP isn't a big deal

I like to give far more magic items than these guidelines suggest, mostly because magic items are a lot of fun. Honestly, I don't think that it's too imbalancing, unless you give one character a lot more magic items than the others. After all, you can always increase the difficulty of your encounters to compensate for the increased power that your PCs will have. Plus, I think that many players enjoy steamrolling a few encounters with their magic items, so even if you misjudge a few encounters, it's not a big deal.

Answer 2

There is nothing to worry about. There is nothing overpowered or unbalanced about this item.

You have allowed a PC to purchase an item which grants +2 AC at the cost of a hand slot (which now prevents him from using two-handed weapons) and requires proficiency. Essentially, he has traded away his ability to inflict damage from range for the ability to inflict a similar amount of damage in melee while taking slightly fewer (melee) hits.

I'll note here that attacking from range already has the added benefit of not putting yourself in harm's way so some might argue this is a downgrade (not being hit at all means you take less damage than whatever hit reduction an additional +2 of AC might grant you in melee). There's a lot of number crunching one could do to analyze the trade-off but I don't think that's necessary here; this is a completely normal item and as a new DM you should wait to see if there is actually a problem before worrying about it.

It's also important to bear in mind that for many classes, a standard shield is a piece of starting equipment. Even if it's not starting equipment for the ranger, it can be purchased from by a PC in just about any settlement for the paltry sum of 10gp.

The linked question is referring to a magical shield which grants +4 total AC, and as noted in that question's comments there are ways to achieve a similarly high AC through only mundane means.

Answer 3

New GM/Player anxiety

Based on your question (and this is not a negative criticism), it seems safe to assume that you have not played D&D a lot in either the player or the Dungeon Master role. It can seem a bit overwhelming to learn to play a new game in the first place, let alone running a game. DM'ing can seem downright daunting and will cause a lot of anxiety. The issue you have based on your question is associated with this anxiety and a lack of practice in D&D terminology.

Personally, I think it's awesome that you chose to dive in to that role. I ran my first session of D&D myself when I was in middle-school. We need more DM's out there, and no matter how much experience you have as a player, you are learning under fire, so don't sweat mistakes that much. You can always adjust the game to fit what you are doing.

Terminology confusion

In D&D you will find running games a bit overwhelming if you haven't played a decent amount before-hand. Some things associated with terminology can be confusing.

When someone refers to a +2 item (such as a +2 shield), they are referring to the fact that it is superior to a normal item of that type (by a numerical value of 2). This means that it is not simply a shield, it is magical enough to offer much better protection (double in this case) than a normal shield.

Naming Consistency

Because different armors all have different AC values, it could get confusing if they named armor based on their AC value/bonus. Plate Armor provides an AC of 18 and studded leather provides an AC of 12 (+dex modifier). It would be more confusing in the long term if both were named based on these factors, so in order to create consistency, they are simply called by those names, but magical variants that provide higher than those values are named based on the amount of improvement (so +1 Plate Armor provides a 19 AC and a +2 Shield provides a +4 AC bonus).

You will get more used to these conventions over time, and the DMG gives guidelines on how frequently to give out magical equipment. If the characters can afford non-magical equipment (and you don't have an in-game reason to restrict the town from having the item, such as a small, poor village not having plate armor), then there's no reason not to let them purchase it.

When should you give magic items?

The DMG has tables on pages 135 and 38 that cover Magic Item Rarity and Starting Equipment respectively. That will give good advice on how frequent magic items should be given out, and even base it on the type of campaign you are running (low, standard, or high magic campaign).

For newer DM's I would recommend standard, so you can get a feel for the items and the system, but that part is up to you.

Answer 4

Don't be concerned about the PC's level, be concerned about their power relative to other PCs in the party.

It's really easy, especially as a newer GM/DM (which you seem to allude to being in your question), to get too caught up in the levels. However, as Icyfire stated in their answer, being overpowered isn't a big deal.

Remember that being a GM gives you the ability to account for your players' power. It's very easy to give a monster a bit more health, a higher attack bonus, or otherwise make an encounter a bit more difficult for a party that has a larger 'power level' than their levels suggest. Issues arise when one particular player possess a much higher degree of power than the rest of thier party.

For example, it may be considered generally 'overpowered' if a group of three level 5 characters had ACs of 20. However, you might find all you have to do is increase a monster's attack bonus from +3 to +5 to 'balance' the encounter. On the other hand, if one PC has an AC of 20 and the other two have ACs of 12, it would likely be significantly harder to balance this properly.

That being said don't nerf the shiny new items your PCs just earned by amping up the difficulty, there's nothing wrong with saying "you have better items, so you'll be fighting stronger monsters" but make sure they feel like the items actually give them a sense of greater power or you'll end up with really unhappy players really quickly.

In the event you do give out an overpowered item:

See if you can subtly boost the rest of your party to a comparable power level before you try 'damage control', however try to keep that player slightly more powered up until the other PCs do something to deserve being on the same tier (either they buy an item or otherwise receive an item).

If you can't afford to boost everyone's power, talk to the player who has the OP item and tell them what happened. As GM, you have the responsibility to discuss how you're affecting items a character has before changing them; you might even reach an agreement with little to no pain. But remember that you also have the right to change it even if they're unhappy about it.

All in all, you're the GM, if you're comfortable balancing encounters with the party's current equipment in such a way that all of your players are having fun, they're not actually overpowered. But if you start to feel like you're losing control, start by talking to them.