How to explain to AD&D player that items that increase Armor Class in DnD5e are overpowered?

Context: I have recently started a campaign with a new player that comes from AD&D background. He wishes to convert and import his character to the campaign. We do that once, I help him with the conversion and checked his stuff, he got 2 magical items lvl3 a bit much but I didn’t mind they were not game-breaking (ring of immunity to poison and mobility boots(longer jumps and a bit of speed up)? His character died, He asked to bring another character this time I let him do, I ask him for his stuff and he says that he has a magical sword and a giant strength belt (lvl6) this is IMO very strong, but again not game-breaking I tweaked a bit the encounter and it went fine.

The thing is that I give 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 defence combat style (which he has)). So I asked how His sword is :

The Items magical sword +2 attack bonus, magical damage, +2 fire damage, +2 AC.

IMO At this level having a CA of 23 (25 with "shield of faith" he plays a paladin) is game-breaking most monster exception the strongest get attack bonus of +4 +6, Meaning that he will only get hit on crit by most monsters, or that I have to send powerful monsters (that is maybe not fine for other players). The first question is that True? 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. Does it exist any rational arguments about this?

For now, I come up with the following arguments:

  • 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 they are only two ways: combat style and feats (heavier armour type or the Medium Armor Master feats (+3 dex))

Does there are other arguments? Or maybe I wrong?

Would a race with bludgeoning, piercing or slashing resistance be overpowered?

The various subtypes of dragonborn in D&D 5e have different elemental resistances (acid, cold, fire, lightning, poison). Tieflings similarly have fire resistance, and I would estimate that a variant tiefling with, say, cold or poison resistance instead would be equally balanced.

However, suppose I want to give a race resistance to one of the physical types: bludgeoning, piercing, or slashing. For example, a dragonborn subtype with slashing as its one resistance, or a tiefling with piercing resistance.

Would this be overpowered?

How do I depower overpowered magic items without breaking immersion?

At one point my party cleric found a magic item that allowed him to pull anything smaller than the item out of it, like a Star Trek replicator. Now nothing is a challenge for him anymore. How would I make the item less powerful without just saying “your item is now less powerful” and breaking the immersion of the game by violating continuity?

Vow of Poverty, overpowered or underpowered?

I have read plenty of things about the Vow of Poverty in forums, and i have seen both opinions expressed.

If i understand it correctly, it does work on the assumption of a linear magic item acquisition from the rest of the party, and it is "balanced" on that assumption. I also do understand that some builds use it to mix/max their character, with synergy of other vows.

My question is, as a mechanic, and if one assumes that this linear magic item acquisition is valid for a party, is it overpowered, underpowered, or balanced. Are there any other aspects i am not aware of?

DnD 5e stealth check, meta game and overpowered stealth hide out of combat

Recently I’ve faced with the following situation and was really surprised with the rules:

Let’s consider the following situation: A party is located in a quite deep forest. They know that there is an enemy camp within 1 mile away also located in deep forest. One player says: “I’m trying to hide”.

In PHB DnD 5e it is explicitly stated (PHB p.177)

When you try to hide, make a Dexterity (Stealth) check. Until you are discovered or you stop hiding …

So he makes a roll and let’s assume the final result is 4. Because player can see the result, he can now decide what he is going to do based on this check. Obviously this check is low, and player says: “I stop hiding”. It is allowed based on the cite above. After that he can try to hide again and re-roll.

In this case DM can notice that this is a meta game and it is not allowed, because character can’t know the roll. In this case, even if this will prevent character from re-rolling directly, it can certainly change his initial plan. Or player can do the following:

Character can make an agreement with his party that he will go behind a tree, hide and then they will try to seek him. In this case it is explicitly mentioned in PHB p. 177 that

Until you are discovered or you stop hiding, that check’s total is contested by the Wisdom (Perception) check of any creature that actively searches for signs of your presence. … When you hide, there’s a chance someone will notice you even if they aren’t searching. To determine whether such a creature notices you, the DM compares your Dexterity (Stealth) check with that creature’s passive Wisdom (Perception) score

So even if character doesn’t know the roll, he can find “how well he hides” with this “test”. This “test” can be made using both passive and active checks. In this case he can definitely find “how good he hides”. If somebody in his party could spot him, character is no longer hidden, because that rule above, if not, character is very likely hidden very well (especially if there was a wisdom guy in a party that was by accident unaware of this activity and the check was passive e. g. with fixed known high value). So if character was spotted he just reties to hide until he rolls high enough to hide from his party checks.

So at this moment our hero is hiding and has a really high roll. So he says that he is travelling towards enemies camp in hiding.

Here are rules from PHB p. 182

While traveling at a slow pace. the characters can move stealthily. As long as they’re not in the open, they can try to surprise or sneak by other creatures they encounter. See the rules for hiding in chapter 7.

The “chapter 7” rule are the one I mentioned above.

Well, since our hero is hiding and he travels in slow pace, he comes to enemy camp and he is still hidden because he “was not yet discovered” (see cite 2 above).

After that hero says “I try to sneak by those creatures remaining hidden”. So since they are not expecting him, they use passive check. Since player already rolled high and that roll value is used against perception checks there is no chance they can spot him, so he automatically (or with very high chance) succeed. In this way he can bypass any guards almost guaranteed.

The same trick can be made with whole party by searching each other and repeating until all are hidden and thus it can be made that surprise is be also guaranteed in first round.

For me it looks like it is 100% correct according to the rules from PHB and it also it looks like extremely broken mechanics. No other check value is known to player before he decides what is he going to do with this ability.

So, eventually:

Is there any fix for this rules published somewhere?

P. S. I think any check should be made at the moment the check is really needed and each moment it should be checked independently.

So in this case you don’t roll when you trying to hide. You roll each time you can be spotted, also you roll on each action you perform, e. g. sneak by e. t. c. because all other checks are performed in the same way. Again even if you somehow block a party from doing that, player won’t try to sneak by a group of goblins when he knows ahead that his roll value is low and already determined.

P. P. S. I’ve also checked several forums and videos and everywhere it is explicitly stated that you make check when you hide and you use this single value to compete perception checks and you remain hidden until you found or you stop hiding. Also everywhere it stated that you can move and sneak while hidden and use that roll value against perception checks. So I am really confused.

What are the features of a Dragonborn Warforged and why is it considered overpowered?

On more than one occasion, I’ve seen the (RAW-legal) option of stacking the Warforged race with the Dragonborn subtype listed as being very overpowered. It’s clear to me that going down this path has some major benefits. However, I’m struggling to figure out what all of the combo’s benefits are. Before you even get in to ACFs, prestige classes, or feats, you’ve already got to cross-reference at least two books just to figure out how Living Construct interacts with Dragonborn/Dragonblood. This hasn’t been easy.

This give me my question – what are the features of a Warforged with the Dragonborn subtype, and what parts of this stand out as overpowered?

Is Adjust Density overpowered?

In the Explorers Guide to Wildemount there are two new arcane traditions: Graviturgy and Chronurgy. When you’re a Graviturgist at second level you get a magic feature called Adjust Density:

As an action, you can magically alter the weight of one object or creature you can see within 30 feet of you. The object or creature must be Large or smaller. The target’s weight is halved or doubled for up to 1 minute or until your concentration ends (as if you were concentrating on a spell).

While the weight of a creature is halved by this effect, the creature’s speed increases by 10 feet, it can jump twice as far as normal, and it has disadvantage on Strength checks and Strength saving throws. While the weight of a creature is doubled by this effect, the creature’s speed is reduced by 10 feet, and it has advantage on Strength checks and Strength saving throws. (EGW p.185)

I’m still pretty new to D&D and its rules and this made me confused. It’s a variant of the Enlarge/Reduce spell but it doesn’t require any spell slots or a saving throw to prevent it from affecting an unwilling target.

I’m new to being a DM and I’m not sure how OP something like this would be at second level. It could completely turn combats on their head if they use Adjust Density against an attacker whos attacks are based on strength.

I have two questions about this magic feature: Is this OP compared to other second level abilities and what can I do to prevent battles being turned on their head with this magic feature?

Is this Way of the Unmastered Monk Subclass overpowered? If so, by how much?

My DM is usually very opposed to homebrew, and I can understand why, seeing as a lot of homebrews are ridiculous, but from a flavor and mechanics standpoint, this is exactly what I’m looking for. I’ve thought of combining classes for our game, but everything I’ve asked has either been ignored or shut down. I’m not trying to outshine other players or do everything, I just want to feel like Yojimbo.

I am currently a kensei monk working towards battlemaster, but I won’t be online until 9 The subclass in question