Is there anything that prevents this "Negative AC armor" creation process to function?

Question

This is a follow-up to a portion of this answer to a previous question of mine pertaining to the lowest possible achievable AC. The question is also slightly different as it pertains to magical armor and is limited in scope to Adventurers League play.

Currently, there are two monsters in the game with an ability to damage a Magical armor's AC value : Zorbos…

Destructive Claws. [...] one such item worn or carried by the creature (the targets choice), magically deteriorates, taking a permanent and cumulative -1 penalty to the AC it offers […]. Armor reduced to an AC of 10 [...] is destroyed.

...And the Demon Lord Juiblex :

Eject Slime. […] Any metal armor worn by the target takes a permanent −1 penalty to the AC it offers [...]. The penalty worsens each time a target is subjected to this effect. If the penalty on an object drops to −5, the object is destroyed.

The destruction clauses are different : one is when the Armor's AC=10, one is when the Armor's penalty=-5.

Now, let's say you take a +1 Plate magic item (AC of 19). Your DM somehow agrees to add a Zorbo into your game (if they can find a thematically appropriate justification), and said Zorbo successfully reduces your Magical Plate's AC 8 times, making it go to AC 11. Then, your DM somehow agrees to add the Demon Lord Juiblex into your game (again, with a thematically appropriate justification), which successfully reduces your Magical Plate's AC 4 times, making it go to AC 7. At this point, you go back to the Zorbo, who successfully reduces your Plate's AC once more. At this specific point, the armor's AC is already lower than 10, and its total penalty is already higher than 5, so, to my understanding, this new reduction doesn't activate either of the 2 destruction clauses. And thus, the Zorbo reduces it again, and again, and again, until the armor reaches a (potentially infinitely) negative AC value.

My question is : is there anything I forgot to consider -- anything that would make the above "negative AC armor" creation process not function within the scope of Adventurers League play ?

For the record, I want such negative AC armor on my Redemption Paladin to symbolize a divine punishment by his goddess (he's been naughty).

Answer 1

An Adventurer’s League DM is supposed to rule against you

In some kind of theoretical “what’s the lowest AC possible?” situation, maybe this kind of interpretation would fly, and likewise, at a personal table, a DM might decide to run things this way—they shouldn’t, but they might—but in the Adventurer’s League, no, this does not work. It doesn’t work because Adventurer’s League DMs don’t have the same latitude that a DM might at their own table, so they can’t really work with you on this the way they might, and all of the reasons that a DM shouldn’t allow this at their own table are reasons why an Adventurer’s League DM really can’t.

Character punishments, like everything else in the game, are there to further the goals of the game: to have fun. Anything that causes players to have less fun is, basically by definition, a bad choice by the DM. There can and should be exceptions for temporary disappointments and set-backs—after all, overcoming challenges is where the fun comes from—but that isn’t really an exception, because they are still being implemented in the name of improving the game’s overall fun, in the long term.

And the Adventurer’s League complicates this: the DM and the players can’t just all agree that something would be fun, and go ahead with it. The game is supposed to be the official adventure, that’s what you’re there for—and also what anyone else who wants to join up is looking for. This kind of change would make the game really not the official adventure any more, and that causes problems in a game that’s meant to be compatible with the Adventurer’s League.

You’ll notice, too, that the rules do not have Paladins get their AC nuked for being “naughty.” The game does not suggest—in fact, it goes out of its way to suggest against—this kind of character punishment. D&D 5e in particular has gone a long way to mitigating and limiting the “falling” of paladins—that is very much a part of the game that players agreed to play. There are rules for what, exactly, causes a divine punishment, and there are rules for what, exactly, that punishment entails. And the Adventurer’s League backs up that every step of the way, limiting DMs from doing these kinds of things to player characters. Fallen paladins in 5e are supposed to lose their paladin powers—and gain other powers, either from another class or as an Oathbreaker paladin. They are not supposed to lose their powers and get nothing.

In a non-AL setting, your table might agree that this situation would be fun. They might agree to go along with it for the sake of more content, to see your character deal with it and resolve the situation. But in the Adventurer’s League, that isn’t really an option. You are meant to play an official published adventure, and none of them include this kind of effect, none of them include any side-quests or storylines for resolving the effect, and none of them are designed to include a negative-AC Paladin as part of the party. Dealing with you is going to cause problems for the party—which might be fine in a personal game where everyone was interested in those problems and their resolution, but that’s not an option in the Adventurer’s League.

Answer 2

Within the scope of Adventurers League play, the obvious problem you're going to run into is that you don't have a Zorbo and you don't have Juiblex, and you certainly can't walk back and forth between them to get them to mess with your armor in just the right way.

You've written that your DM "somehow agrees" to do this, with thematically appropriate justification. But that's not how Adventurers League works. An Adventurers League table will be running an official Adventurers League adventure (as described here) and this adventure will not have Juiblex in it.

If you sit down and Iyoutell the DM: "hey can you do me a favor, can we think of a reason Juiblex is in this adventure just enough to wreck my armor", it's not going to go well.

If you somehow get your buddy to be your DM, I guess you could get your buddy to narrate Juiblex into the adventure for you -- but at that point, most people would probably say that it's not really an Adventurers League game any more.

(I'm sorry for guessing at your plan here, but you're being very cryptic about what you're actually planning to do:) In theory, you could get your DM-buddy to write on your equipment list that your armor has been shredded in this way -- but, even then, if you take this equipment list to some other DM, they might audit your equipment list and notice irregularities and conclude that you're engaged in a very strange form of cheating.

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None of this is addressing the questionable math you're doing, where the Zorbo's monster description accidentally omits the words "or less", and you're interpreting this as a real rule and not an oversight. This is also a problem, but it's much less of a problem than the thing where you don't have a Juiblex or a Zorbo; if you have a DM that is friendly enough to provide those monsters, then you also have a DM that is friendly enough to interpret the rules super-literally for you, so this shouldn't cause any problems beyond what you already have.

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The right way to do this is just to tell your Adventurers League DM: "Hey, I'd like to narrate that my paladin is under a curse and his AC is lower than normal, is that cool?" Many DMs will probably be fine with this -- certainly they'd be more likely to be okay with this then "I'd like to narrate that my armor got partially shredded by Juiblex in a previous adventure".

You've written that you want to do this "fully legally", but I think that's misguided. DMs issue rulings for in-game effects all the time; issuing a ruling to describe your curse would be just part of the job. But it's super weird and unusual to narrate a CR23 monster into an adventure and have it not kill you. I think that, instead of "legally", you should try to do this "realistically".

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One final note: most people who are playing Adventurers League are sincerely trying to succeed at the adventure. If you show up with a character who is intentionally terrible, and if this decreases the group's chances of succeeding at the adventure, people might feel like they didn't want to play with you any more. So maybe an even better way to do this plan would be to find a game that wasn't an Adventurers League game, and that had players that wouldn't mind if you did something like this.

Answer 3

Why go through all this trouble?

It seems like your goal is here to create a punishment for your 'naughty' paladin. The method you have constructed is incredibly complex, requires the AL DM to build encounters specifically for you and you alone, and you still need to actually be hit by those monsters (which is not guaranteed.)

However, you are in total control of your own character and if at times you'd like to 'punish yourself', why not just opt to not wear armor at all? I've often played characters who have chosen to be unarmored (although not my paladin, but there were times when i was forced to fight without it.)

Answer 4

From a strict RAW perspective, this works

I go into a similar procedure using Juiblex and a Gray Ooze in this related question. Since the AC bonus of the armor never reaches the destruction levels (as it is already below it), the armor continually goes down. Here is the relevant section from my answer:

The first step is to get hit by Eject Slime 4 times (3 times for Chain Shirt). This reduces the armor class granted by the armor to 10, but does not destroy it as that would require a 5th reduction from Juiblex:

If the penalty on an object drops to −5, the object is destroyed.

Then you just need to get repeatedly punched by the Gray Ooze. After the first Pseudopod, the armor bonus is reduced to 9, which does not meet the clause:

The armor is destroyed if the penalty reduces its AC to 10.

... since it specifies exactly 10 (not less than 10). Then you can repeat this procedure and the armor gets progressively higher penalties as long as you can continue to survive the attacks (which the right character can survive forever).

Now, clearly this is nonsensical, as acid shouldn't be able to suddenly make your armor class lower than if you weren't wearing armor at all, but that's how the rules work together as written.

Your variation is just using Zorbos' effect rather than the Pseudopods of the Gray Ooze.

Answer 5

This would not be a punishment as long as they can doff the armor.

From the PHB p 14:

Without armor or a shield, your character's AC equals 10 + his or her Dexterity modifier.

So, with an average dexterity modifier they would still have an AC of 10. If they have a negative dexterity modifier then the AC would go down. With standard array or point buy you would always have at least an AC of 9 unless a spell or other feature reduces your Dexterity further.