20
\$\begingroup\$

This is a direct, somewhat silly, opposite question to What is the highest possible AC? .

I’m wondering what is the lowest possible Armor Class a Player Character can get at any point in time, “helped” by any official relevant monstrous feature, magic item, spell, etc.

So far, the lowest I’ve obtained is a 0, provided that the player character is a (Monk or Barbarian) with both Dexterity and (Constitution or Wisdom) rolled as a 3 (-4) without any racial bonuses to said stats and that said character is affected by a Slow spell.

Can you go even lower than that ?

\$\endgroup\$
  • 16
    \$\begingroup\$ It amuses me that this has the [optimization] tag... \$\endgroup\$ – NathanS Jun 28 at 22:12
  • 4
    \$\begingroup\$ Being able to laugh at an enemy who misses you despite a low as heck AC is what I would call an optimized character. \$\endgroup\$ – Gael L Jun 28 at 22:16
  • 1
    \$\begingroup\$ Is using wish to get a low AC or lower ability scores valid for this question? \$\endgroup\$ – Medix2 Jun 28 at 22:42
  • 3
    \$\begingroup\$ @medix2 Hmmm, let’s say no. \$\endgroup\$ – Gael L Jun 28 at 22:50
  • 4
    \$\begingroup\$ @Medix2: I suspect wish needs to be excluded right out of the gate for most such questions because you can do pretty much anything with it - if the DM allows it. \$\endgroup\$ – V2Blast Jun 28 at 23:30
22
\$\begingroup\$

The lowest reasonably achievable Armor Class is -7

The Character

The character, lets call him Colby, to accomplish this absurdly low AC is a character with rolled ability scores resulting in 3 Dexterity, 3 Charisma, and either 3 Wisdom or Constitution.

If 3 Wisdom, Colby requires at least 1 level of Monk, and 3 Constitution requires at least 2 levels of Barbarian.

The Gear

Colby needs these magic items:

  • Chromatic Dragon Mask (found in an adventure module below)

Hoard of the Dragon Queen and Rise of Tiamat

  • Book of Vile Darkness
  • Wand of Orcus, Sword of Kas, or Orb of Dragonkind

Each of the artifacts have major detrimental properties (the Book of Vile Darkness has 2). One option of which is:

$$\begin{array}{|c|c|} \hline \text{}&\text{When you become attuned to the artifact,} \\ \text{76 ‒ 80}&\text{one of your ability scores is reduced by 2} \\ \text{}&\text{at random...} \\ \hline \end{array}$$

These reductions need to affect Dexterity, Charisma, and whichever of Wisdom and Constitution is low.

The Calculation

With the gear mentioned above, and the slow spell, you get this Armor Class:

  1. With Dexterity and Constitution or Wisdom at 1 are AC with Unarmored Defense is 0

While you are not wearing any armor, your Armor Class equals 10 + your Dexterity modifier + your Constitution modifier (Wisdom modifier for monk).

  1. The Chromatic Dragon Mask has the following effect:

Draconic Majesty. While you are wearing no armor, you can add your Charisma bonus to your Armor Class.

This results in another -5 to AC, for AC of -5 so far

  1. The slow spell.

An affected target's speed is halved, it takes a −2 penalty to AC and Dexterity saving throws, and it can't use reactions.

Finally, with 2 less AC, we are at an AC of -7


Strict RAW

A strict adherence to rules-as-written provides another answer:

There is no lower bound

You can reduce armor class infinitely with a special procedure.

The Garb

The attire for the infinitely regression of AC is one of the following armors:

  • Chain Shirt
  • Scale Mail
  • Breastplate
  • Ring Mail

The Monsters

There are two monsters required to reduce your armor class forever.

  1. The demon lord, Juiblex

Juiblex has an ability called Eject Slime which says:

Unless the target avoids taking any of [the acid damage from this attack], any metal armor worn by the target takes a permanent −1 penalty to the AC it offers, and any metal weapon it is carrying or wearing takes a permanent −1 penalty to damage rolls. 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.

  1. Any number of ooze monsters including the Gray Ooze whose Pseudopod attack includes:

if the target is wearing nonmagical metal armor, its armor is partly corroded and takes a permanent and cumulative −1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10.

The Procedure

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.

\$\endgroup\$
  • 3
    \$\begingroup\$ I'm not that confident that this reasoning still holds in 5e, but does really "you can add your charisma bonus" mean you can add your charisma malus? D&D used to call the net value "modifier", while a bonus is always positve and a malus negative. \$\endgroup\$ – Zachiel Jun 29 at 13:05
  • 3
    \$\begingroup\$ @Zachiel It is hard to tell. Probable worth its own question. There are many instances where the rules say "ability modifier" which definitely allows for negative modifications. I've not found many examples of "bonus" where the rules don't say "(minimum of +1)" \$\endgroup\$ – David Coffron Jun 29 at 13:36
  • \$\begingroup\$ I think thatn, when the rule does say "(minimum of +1)" the modifier is what's equal to the largest of your bonus or the +1. So you still get a +1 if you have no bonus or a malus to that ability score. \$\endgroup\$ – Zachiel Jun 29 at 13:38
  • \$\begingroup\$ @Zachiel right, but this instance of "bonus" doesn't have that, so it is unclear. \$\endgroup\$ – David Coffron Jun 29 at 13:43
  • \$\begingroup\$ Most of my experience is with pre-5e, but I also remember something about how a "bonus" could never drop lower than +0, a "penalty" could never rise higher than -0, and a "modifier" was unbounded. \$\endgroup\$ – Draconis Jun 30 at 0:51
10
\$\begingroup\$

Minimum achievable AC: -5

Requirements:

  • At least 1 level of the Monk class.

  • Ability scores must include 3 Dexterity and 3 Wisdom.

  • Don't wear armor.

  • Access to someone who can cast the slow and feeblemind spells.

  • Be playing the Rise of Tiamat adventure module, and acquire a Dragon Mask, an item with the following property:

Draconic Majesty. While you are wearing no armor, you can add your Charisma bonus to your Armor Class.

The calculation:

  • The monk's Unarmored Defense sets your AC as 10 + Dexterity bonus (-4) + Wisdom bonus (-4).

  • Be affected by a feeblemind spell, which drops your Charisma score to 1. If you wear the Dragon Mask, then it adds your Charisma bonus (-5) to AC.

  • Be affected by a slow spell, which gives a -2 penalty to AC.

Total = 10 -4 (Dex) -4 (Wis) -5 (Cha) -2 = -5

\$\endgroup\$
  • \$\begingroup\$ "Dragon Mask: Draconic Majesty. While you are wearing no armor, you can add your Charisma bonus to your Armor Class.' Sorry but note that the keyword "bonus" is used, not the keyword "modifier". A negative modifier to a stat, say -2, is the same as saying you have a -2 negative penalty to that stat, while also having a +0 bonus to the stat. Penalties can only be negative, and bonuses can only be positive. \$\endgroup\$ – Pat Sep 7 at 3:56
0
\$\begingroup\$

Ok, lemme try:

Character creation:

  • PC is either Barbarian (main stats: DEX and CON) or Monk (main stats: DEX and WIS).

  • PC is from a race does not synergize at all with his class. i.e. zero racial bonuses to any of his two "main stats" above.

  • Player rolls for stats and... gets incredibly unlucky, rolling 3 for both main stats!

His AC is already only 2!

Note that the odds of this occurring is already = 1 / (6^6) = 1 / 4665600 !

Also:

  • Cursed by his player: Player somehow decides that PC will use all of his "can use" abilities that would end up lowering his AC anyway instead. Just because, ok? Similarly, even if a simple spell would get rid of a negative condition, PC won't seek help!

Magical items:

Not this one:

Dragon Mask: Draconic Majesty. While you are wearing no armor, you can add your Charisma bonus to your Armor Class.

Note the emphasis is to the word "bonus", not to the word "modifier". A bonus is always, at worst, +0, even if the modifier is negative. Thus, you can't get a penalty to AC from this item!

However, cursed items definitely do exist!

  • Cursed Bracers of Defense: -2 AC instead of +2 AC seems very reasonable.

His AC is now 0!

But a cursed Dragon Mask that gives a penalty to AC instead of a bonus, that would be "stretching it a little bit topo much", though.

  • Book of Vile Darkness:

(or any combo of two artifacts that each give 1 major detrimental effect)

PC doesn't increase any of his main stats, and, by purest bad luck, both of the major detrimental properties just happen to be:

76-80 When you become attuned the artifact, one of your ability scores is reduced by 2 at random. A greater restoration spell restores he ability to normal.

And by pure random chance, both of his main stats, again, are those affected!

AC is now -2!

Spells

  • Slow: -2 AC.

Worst AC = -4!

Unless you fight a really, really bad enemy, unless they roll a Natural 1, they hit!

Note that actually trying to get hit would be, at the very least, just as bad as being attacked while unconscious.

And the final odds of bad luck required for that freak sequence of results to even be possible are now:

1 / 335923200 !

And that is not even counting the adventuring odds of finding the needed artifact(s).

Ouch!

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.