How do I explain to an AD&D player that items that increase Armor Class in D&D 5e are overpowered?

Question

Context: I have recently started a campaign with a new player that comes from an AD&D background. He wishes to convert and import his character to the campaign. We did this once, and I helped him with the conversion and checked his stuff; he got 2 magical items at 3rd level. A bit much, but I didn't mind as they were not game-breaking (ring of immunity to poison and mobility boots[longer jumps and a bit of speed up]). Then this character died, and he asked to import and convert another character. This time, I asked him for his stuff and he says that he has a magical sword and a giant strength belt as a 6th level character. This is, IMO, very strong, but again not game-breaking, or so I thought; I tweaked a bit of the encounter and it went fine.

The thing is that I gave him a full plate armour and then he says that his armour class was 23. I was surprised because Max AC without magic is 20 - 21 (with Defense fighting style, which he has).

The Item: a magical sword with +2 attack bonus, magical damage, +2 fire damage, and +2 AC.

In my understanding, at this level, having an AC of 23 (25 with shield of faith, he plays a paladin) is game-breaking. Most monsters encountered at this level get attack bonus of +4 to +6, meaning that he will only get hit on crit by most monsters, or that I have to send exceptionally powerful monsters for this level, which may not be appropriate for other players.

Is this AC game-breaking at level 6?

I started to talk about this. and it went bad. He says that it is only 8 % increase of AC and did do much and that he gains his sword on a very deadly quest etc. Maybe it is a good computation in AD&D setting but in 5e I feel it is not.

For now, I have come up with the following arguments why the sword providing +2 AC is overpowered:

• AC doesn't scale the same, and 21 is already the maximum you should expect to be. A venerable red dragon AC is 22.
• AC increase is extremely costly, with non-magical means; there are only two ways: combat style and feats (heavier armour type or the Medium Armor Master feats (+3 dex))

Answer 1

+2 AC is much more than an 8% improvement, in one case it is as high as 200%.

Erik's and Quadratic Wizard's answers do a fine job of comparing the proposed item to existing magical items in the DMG. The trouble is, if I only believe it is an 8% improvement in AC, I'm going to conclude that the DMG is wrong about how strong +2 AC is. So it seems good and necessary to actually correct the notion that +2 AC is only an 8% improvement.

Sure, the number increases from 21 to 23, which is an improvement somewhere between 8-10%. But that is not how we measure the effectiveness of AC or how much it improves when we increase it.

Consider the following table. Column 1 shows the hit bonus of the attacking creature. Columns 2 and 3 show the probability of that creature hitting ACs 21 and 23, respectively. Column 4 shows the percentage of attacks that would hit AC 21, but miss AC 23. Finally, column 5 shows the percentage improvement in survivability of the change in AC. Column 5 is how we determine the marginal effectiveness of a change in armor class.

Hit Bonus	AC 21	AC 23	% of attacks that hit AC 21 but miss AC 23	Change in Survivability
0	5%	5%	0%	0%
1	5%	5%	0%	0%
2	10%	5%	50%	100%
3	15%	5%	67%	200%
4	20%	10%	50%	100%
5	25%	15%	40%	67%
6	30%	20%	33%	50%
7	35%	25%	29%	40%
8	40%	30%	25%	30%
9	45%	35%	22%	29%
10	50%	40%	20%	25%
11	55%	45%	18%	22%
12	60%	50%	17%	20%
13	65%	55%	15%	18%
14	70%	60%	14%	17%
15	75%	65%	13%	15%
16	80%	70%	13%	14%
17	85%	75%	12%	13%
18	90%	80%	11%	13%
19	95%	85%	11%	12%

As you can see, even against the mighty Tarrasque (+19 to hit), the improvement is still better than 8%, sitting around 12%. But we aren't fighting a Tarrasque at level 6. As mentioned in your question, we're looking more in the range of +4 to +6 to hit, which gives +2 AC an improvement between 50% and 100%, which is quite significant. On average, half of the +4 to hit attacks that would have hit me before now miss me. In terms of survivability, this doubles my durability. Increasing my AC from 21 to 23 means I can last twice as long (on average) against a creature that has a +4 to hit. That's a 100% improvement. Not 8%.

How powerful is AC 23 at 6th level?

It's pretty powerful. As in, most encounters at this level will pose virtually no risk of harm. But let's try to set up something of an experiment and run some numbers.

Say our paladin with an AC of 23 is out adventuring solo and gets attacked by three blue dragon wyrmlings.

A blue dragon wyrmling has +5 to hit and deals 1d6+1d10+3 (average 12) damage on a hit. Consulting our table, the blue dragon wyrmling has a 15% chance to hit our paladin with an AC 23. Thus, the average damage sustained by our paladin each round is:

$$3 \times 0.15 \times 12=5.4$$

A 16 CON paladin taking the average increase for hit points each level will have a modest 58 hit points, which means our paladin can be expected to last for 10 rounds before dropping in the 11th round, assuming he doesn't use any healing spells or lay on hands. For simplicity the wymrlings didn’t use their breath weapons at all.

Reworking this scenario for an AC of 21, we have:

$$3\times 0.25\times 12=9$$

With an AC of 21, the same Paladin can be expected to last 6 rounds before dropping in the 7th. To be clear, 6 rounds without dropping is nothing to scoff at, it is quite resilient; but it demonstrates just how much more powerful an AC of 23 is.

You take this absurdly reliable talent for not getting hit by attacks and spread those attacks out across the party, and this paladin will rarely have to polish his armor.

Now, I would be remiss if I did not mention that AC is not the only part of combat survivability. An armor class of 30 will do you no good against spells that damage on failed saving throws. But AC is still a huge part of combat survivability.

I get that this is oversimplified in comparison to actual combat. But I think it demonstrates the point well enough. In my party of 5, our Paladin plays the tank role very well. Most of our combat encounters are 3-5 rounds and we have 1 or 2 per 4 hour session. We are also 6th level, his AC is 19, and I still feel that he almost never gets hit. From experience, 19 is very good. An armor class of 23 is broken.

So what do I do?

This question has some great suggestions for handling this in a way that is engaging and fun for both the DM and the player: I gave a too powerful magic item at too low level for a bad reason, what to do? This situation is a little bit different than the specific situation detailed there, but the ideas and principles can still apply. Finally, Dale M's answer gives some good advice for dealing directly with the situation.

Answer 2

Refusing to allow overpowered custom items from another campaign is an AD&D tradition.

Even in AD&D, the Dungeon Master's Guide recommended against allowing a player to bring powerful custom items or characters from another campaign. The AD&D 2nd edition revised DMG, p.14, on "Super Characters", even cites the specific example of a character bringing an overpowered custom magic sword from another campaign.

When someone brings a character from a different campaign and wants to use him in your game, compare the proposed character to those already in the game. You don't want him to be too strong or too weak. [...]

If you decide a character is too powerful, the player has two choices. First, he can agree to weaken the character in some fashion (subject to your approval). This may be as simple as excluding a few magical items ("No, you can't bring that holy avenger sword +5 that shoots 30-dice fireballs into my campaign!"). [...] If this sort of change seems too drastic or requires altering ability scores or levels, a better option is simply to have the player create a new character. Remember that just because another DM allowed something is no reason you have to do the same!

His items are also more powerful for his level than the rules recommend.

Another reason is that D&D 5th edition has specific guidelines on starting treasure, appearing in the 5e Dungeon Master's Guide p.38, "Starting at Higher Level". In a standard campaign, a level 6 character (if I read the question correctly) doesn't get any items, and in a high-magic campaign he receives only one uncommon item. Two uncommon at 6th level isn't game-breaking, but we must look at the balance of his particular items.

• A belt of hill giant strength, which raises Strength to 21, is a Rare item. The gauntlets of ogre power, which raise Strength to 19, are Uncommon.
• A sword which gives +2 attack, +2 fire damage, and +2 AC is as good as multiple items:
  • A weapon +2 (giving +2 attack and +2 damage) is a Rare item. Dealing that +2 damage as fire isn't much more powerful; it's just changing type. As per DMG p. 294, "Modifying an Item": "an item that deals damage of one type can easily deal damage of another type."
  • Armor class +2 is at least as powerful as if it were a separate Rare item, as per DMG p.285: "If an item delivers a static bonus to AC, attack rolls, saving throws, or ability checks, this column suggests an appropriate bonus based on the item's rarity." However, the Armor +2 has a rarity of Very Rare. There are other items of +1 AC, which are only Uncommon to Rare, so an AC bonus item is not unprecedented, but with the exception of the Legendary rarity +3 Defender, the only items in the DMG which give a +2 bonus are armor and shields. The DMG also notes that combining two items into one is entirely reasonable, but it can increase the item's rarity. In other words, this sword is at least Very Rare.

In other words, the main issue is not that a sword could grant an AC bonus, per se, but that such an item would be at least Very Rare, which is normally too powerful to be given out to such a low level character.

Suggestion: Allow the items but limit their power

If you allow the player his items, but constrain their numbers to more closely match the norms in D&D 5th edition, you can retain most of the game balance without upsetting the player by revoking their prized items.

I recommend limiting the belt's Strength to 19, and the sword's AC bonus to +1. A reasonable explanation is that numeric bonuses tend to be smaller in D&D 5th edition, and it's important to retain balance. You might also suggest that the character or their weapon has come from a parallel Material Plane, and invoke the AD&D tradition of weapons losing a plus when on another plane.

Both the belt and sword should require attunement, meaning that the character can only have one more attuned item. This limits the ability to stack these powerful items with more powerful items.

Do not place +2 or better full plate armor as treasure. A big issue with an AC bonus sword is that it could be stacked with magic armor.

Remember that AC is still only one statistic. Many enemy attacks require saving throws instead, which the character will not be immune to. A min/maxed AC paladin is not unthinkable (they might instead have taken one of many items granting +1 AC, which is still high), but a very high AC is not entirely unreasonable on a defense-oriented character, as long as they are not entirely invulnerable to harm.

Answer 3

Start with “I made a mistake”

It’s not his fault that you allowed him inappropriate items and now you need to be mean and take his stuff away. Especially since it seems clear that you didn’t actually check what they were first.

By all means explain why you were wrong but don’t forget that’s just a salve for your conscience - just because you’re taking his stuff for a good reason doesn’t change the fact that you’re taking his stuff.

So, having realised what’s really going on and why he is legitimately upset about it, you need to decide what to do about it.

1. Apologise. You screwed up, tell him you did so and that you’re sorry that your screw up has created this situation but that now that you are here the two of you have to agree on how to go forward.

2. You can explain why this sort of item is not present in D&D 5e. Don’t expect your arguments to be simply accepted but if you do step 1 properly , they might be listened to.

3. Find a solution:

   1. At one end, this is the item goes or he goes. You’re the DM, you do have the authority about what you do and don’t allow in his game.
   2. At the other end, he gets to keep it. It’s not game breaking. Sure it makes him harder to hit but you can deal with that by:

   a. Having more monsters trying - a 2 step improvement in AC is more than offset by being the target of one additional attack

   b. Using effects that need saving throws not attacks

   c. Grappling and shoving.

Answer 4

The closest weapon to this in 5e is Defender. But this is a Legendary weapon, so not suitable for a level 6 character. It is also worse than your player's sword, since it cannot give both a +2 to attack and a +2 to AC at the same time. You have a total of +3 to distribute between attack and AC.

Giving a more powerful item than a Legendary weapon to someone at level 6 is going to break things. If you remove the +AC it should be OK.

Answer 5

The best argument is looking at the Magical Items chapter in the DMG to see roughly how powerful his weapon is. It sounds like he is equipped with a combination of a +2 weapon and a +2 armor in a single item (in terms of power)

Check the table in the DMG on page 135.

A +2 Weapon is a Rare item, which is appropriate for a character of level 5+, so your player might conceivably have one.

However, a +2 Armor of any type is a Very Rare treasure, suitable for a character of level 11+.

Both of these combined into a single item is a lot for a single 6th level character.

Note that if you look at the random-roll tables, +2 Armor only starts appearing on Magical Item Table I, which will rarely show up for a treasure hoard of challenge rating 11+.

All things combined, this item seems much too powerful to be in the possession of a 6th level character.

For some tips on how to bring it back to a more regular level:

You might reduce the bonus to +1 (which makes it a combination of an Uncommon and Rare item; still very potent at that level) or remove the AC bonus entirely to be left with basically a Rare item (which is reasonably to have at hat level)

Answer 6

Explain that the issues are about the whole party as a whole, not just one character's high AC

I played in a game where an elven bladesinger at level 2 had an AC of (if I remember right) 21 normally, 26 with shield. The highest AC of the rest of us was 15 or 16.

The DM had a lot of problems challenging the party. Anything that was a threat to the bladesigner (i.e. something with attack bonus high enough to hit on more than a 20) would wreck the rest of us. Anything that was a reasonable threat for us wouldn't touch the bladesinger, unbalancing combat (since the bladesinger never got hit and never lost concentration).

Additionally, when the monsters only hit you on a 20, that means evry single hit is a critical. When the bladesinger did get hit, he got hit with massive damage, which almost always broken concentration.

Answer 7

For now, I have come up with the following arguments why the sword providing +2 AC is overpowered:

• AC doesn't scale the same, and 21 is already the maximum you should expect to be. A venerable red dragon AC is 22.
• AC increase is extremely costly, with non-magical means; there are only two ways: combat style and feats (heavier armour type or the Medium Armor Master feats (+3 dex))

Neither of those arguments particularly make sense to an AD&D 1e/2e player:

• He expects to have better AC than opponents, and views it as necessary for survival.

• Non-magical ways of increasing AC are alien to him, apart from DEX, and he probably doesn't appreciate their impact.

You may do better by explaining that, while AD&D1e/2e were extremely compatible with each other, 3.xe, 4e and 5e are all different game systems, with different assumptions, different strategies for character development, and different combat balancing. The amount of terminology and general ideas of play they have in common is misleading, when you get to detailed mechanics. They are effectively different games. Porting characters between them works rather poorly for characters who are even slightly complicated, or designed in styles different from those that the designers of different editions used.

This is why I still play AD&D1e: my characters and the setting I run don't translate well, and I've never felt motivated to start again from scratch.

Answer 8

Lots of comments about how overpowered the weapon is, but no real way of handling the problem itself - which is that you let this weapon through, didn't check it, and now you face the problem of dealing with a player who is unhappy with your house rules.

Drop the magical bonus to AC completely - but give the sword 1d4 fire damage. The sword has a spirit bound within it, and that spirit is trying to escape. Add it to your story. Give the paladin a quest to free it, or redeem it, or something. Send enemies after the paladin, trying to reclaim that sword. Make it a dangerous thing to have, a powerful weapon.

Sometimes the sword won't cooperate - you're a DM, so you play the sword. Maybe it has morals that won't let it do certain things. Maybe it resents being bound. Maybe it's a demon or a devil forced to the will of another paladin, or a bound lantern that doesn't want to be involved in mortal affairs. Occasionally, it will cooperate and suddenly your player has +2AC again.

Yes, the weapon feels overpowered, and it should, because you made that mistake. What you can do now is include that power into the story in a way which doesn't break the character. If they are keen about having the sword because its their sword, rather than the power, they will go along with it. If they are keen about having the power, you dealt with a problem before it became one.

If you are trying to kill your characters with stats, don't bother. They will always win. But there are about fifty million ways to kill a character in DnD with story.