Vorpal Sword Mechanics

A Vorpal Sword is a slashing weapon that decapitates on a critical hit. Even experienced Dungeon Masters are wary of allowing a Vorpal Swords in their game–probably because they have heads. Since Vorpal Swords are some of the most fun you can have with your scabbard on, let’s figure out how to make them work.

Vorpal Mechanics

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In AD&D 1st and 2nd Edition, a Vorpal Sword would sever an armored humanoid opponent’s head if you rolled a 20, after applying bonuses. So basically you were lopping off heads with 20% of your attacks. This was harder against larger creatures (18-20) and stone/metal creatures (19-20). Some creatures were unaffected (doppelgangers, elementals, golems). This gets pretty absurd when you realize that with three attacks, you’ve got a 48.8% chance to vorpalize an armored humanoid.

In 3rd Edition, “vorpal” was a weapon enchantment for slashing weapons that would decapitate on a critical hit. The player who rolled a natural 20 with a Vorpal Sword would roll again to “confirm” their critical hit before lopping off the heads of their foe. The confirmation reduces your vorpal per attack chance from 20% to less than 5%.

In 5th Edition, the Vorpal Sword was installed as a legendary item. With this change, the “confirm” roll was abandoned, instead allowing the player to decapitate their foe on a natural 20 attack roll. This is tempered by immunities granted to creatures who don’t have or need heads (obvious), are immune to slashing (even though the weapon ignores slashing resistance), has legendary actions, or is too big. Instead, these creatures take 6d8 damage.

Chance to Vorpalize an Armored Humanoid

Critical Range AD&D 3rd Edition 5th Edition
Crit. on 20 0.25%-4.75% 5%
Crit. on 19-20 0.25%-4.75% 5%
Crit. on 18-20 0.25%-4.75% 5%
Crit. on 17-20 20% 0.25%-4.75% 5%

History of Vorpal Power

One, two! One, two! And through and through
The vorpal blade went snicker-snack!
He left it dead, and with its head
He went galumphing back.

–Lewis Carroll, “Jabberwocky” 

While Alice never divined the true power of the vorpal blade (her progenitor Carroll writing “I am afraid I can’t explain ‘vorpal blade’ for you”), Gary Gygax gave the vorpal blade life in Dungeons & Dragons.

Gygax ran with Carroll’s decapitation flavor text and scattered Vorpal Swords throughout the realms in old school TSR products:

In 3rd Edition, the vorpal enchantment was the highest roll on the random Melee Weapon Special Abilities table (Major 77-80), with everything above being “roll twice” (81-00). At market, the cost of a vorpal enchantment was +5, the highest available modifier. In order to craft the vorpal enchantment, you’d need to have a feat to create magic items, a good weapon, and access to high-level Necromancy magic (i.e. Circle of Death).

In 5th Edition, the Vorpal Sword is a legendary item. While it’s not an artifact, the vorpal mechanic is not available to artifact weapons on the Artifact Properties tables (Dungeon Master’s Guide p. 219).

Historically, vorpal is the most powerful weapon mechanic in D&D. Keep that in mind when considering its mechanics.

5e Mechanics and Interactions

Reducing the vorpal trigger to a natural 20 was an elegant solution.

However, it seems that it was inelegantly implemented. In 5th Edition’s rush to return everything to its simplified roots, the Vorpal mechanic became the most complicated it’s ever been. Now you have to remember four different exceptions, in which case the Vorpal Sword does damage instead of the thing it does.

I preferred the AD&D treatment where it was harder to vorpalize bigger creatures, hardest to vorpalize stone/metal creatures, and impossible to vorpalize headless stuff. Because that still follows the flavor of doing the thing it does. However, this was previously accomplished by expanding the critical range–the very thing that made the Vorpal Sword overpowered in AD&D. Instead of implementing these myriad rules, I direct your attention to this 3rd Edition rule that is maybe the least 3e thing ever:

DM Calls.png

That’s right: make a call. Just use your head (if you still have one).

I’ve heard D&D players say that the reason Vorpal is so dangerous is due to interaction with other dice manipulation mechanics. Frankly, I believe these concerns are overblown. Let’s examine how much of an affect they have, and whether it’s something that needs to be addressed.

Lucky Feat

“When you make an attack roll…you can…roll an additional d20. You choose which of the d20s is used for the attack roll…”

First we must acknowledge that Lucky is the most maligned and powerful feat. As such, it should not be an indictment against a separate mechanic that interactions with Lucky render it broken. With that being said, let’s see how bad it is and what we can do to work around it.

You can only use Lucky once for each vorpal attack you make. This essentially lets you roll with advantage. While your chance to trigger Vorpal on a straight roll is 5%, Lucky adds 4.75%.

Assuming you attack three times and burn all three luck points, your odds of triggering a vorpal strike are 26.5%. That’s significant, but still much less than AD&D’s 48.8% on three attacks. Compare this with the 14.2% chance to trigger a vorpal strike without Lucky after three attacks. I’m comfortable with a feat that adds 12% to your chance to instakill. If that’s all it’s being used for, I’m convinced that other feats can have a greater impact on the battle.

% to Vorpalize 5th Edition Lucky Feat (5th) AD&D
One Attack 5% 9.75% 20%
Three Attacks 14.2% 26.5% 48.8%

Always keep in mind that bad guys can by lucky too: “If more than one creature spends a luck point to influence the outcome of a roll, the points cancel each other out; no additional dice are rolled.” To keep it balanced, I burn luck points as Legendary Resistances.

If this still bothers you, the problem is probably Lucky, not the Vorpal Sword.

Halfling Lucky Racial Trait

“When you roll a 1 on the d20 for an attack roll…you can reroll the die and must use the new roll.”

This ability adds a miniscule chance to vorpalize. Halfling Lucky only triggers when you roll a 1, and then you must roll a 20 after rolling that one to activate vorpal. The chance of activating a Vorpal Sword due to the Halfling Lucky racial trait is 0.25% (1-in-400).

Wizard School of Divination Portent 2nd-Level Ability

“When you finish a long rest, roll two d20s and record the numbers rolled. You can replace any attack roll…before the roll…only once per turn.”

Your chance of rolling at least one 20 on your portent dice at the beginning of the day is 9.75%. This does not bother me. By the time the party finds a Vorpal Sword, the Wizard probably has a few things in their bag of tricks that have a greater than 10% chance of killing the BBEG. On the chance the Wizard wakes up on the destined day of the BBEG scrum and rolls a 20, then perhaps fate has it in the cards that the Vorpal Sword will win the day. That still doesn’t make it easy.

If you sense yourself thinking that the players might cheese the Divination dice, don’t let them. If you aren’t comfortable telling a player straight up to “cut the nonsense” (which I recommend), then apply narrative pressure: “sure, you can wait until tomorrow to reroll your Portent dice, but the BBEG will have wiped out the militia that’s supposed to support your attack, leaving you virtually no chance of success.” If your BBEG is vulnerable to attack, the window should be limited.

The Fix: Confirmation Rolls

The best kept secret about the 3rd Edition vorpal confirmation mechanic is that even though you’re making it harder on the player to succeed with vorpal decapitation, you’re doing it by employing the two most fun things in D&D: suspense and rolling dice. Now, when the player rolls a critical hit, they’re not just amped about dealing double damage, they’ve won a golden ticket to the vorpal lottery!

There are several ways to build the vorpal confirmation mechanic:

  • Natural 20s Only. In the spirit of 5th Edition, you can require another natural 20 to confirm the critical hit. This will leave some pretty slim odds of decapitation.
  • Critical Confirmation. You can require a second critical roll to confirm decapitation. While this will function identically to the Natural 20s Only rule in most situations, it would be a boon for the Champion Fighter, which is notoriously underpowered. If this applies in your game, you can require the critical or the natural 20 on the attack roll or the vorpal confirmation roll–the odds are the same.
  • Hit Confirmation. In the spirit of 3rd Edition, if the player rolls a natural 20 with a vorpal weapon, make them roll another d20, adding their attack modifier against the opponent’s Armor Class (AC) to confirm the hit. This is a nice middle-ground that tempers the 5% vorpal success without straining the odds to 1% or less.
  • Damage Dice Confirmation. Stealing a little from 4th Edition’s bastardized vorpal mechanic, you can confirm a decapitation when your player rolls maximum damage dice on a critical hit. This has the odd effect of making larger weapons harder to confirm vorpal hits (especially greatsword at 2d6), but perhaps that works thematically for you due to the greater maneuverability of a smaller blade.

I recommend calling the confirmation the “vorpal roll” instead of an “attack roll.” This skirts nicely around all the funny business with the Lucky feat, the Halfling Lucky racial trait, and the Diviner’s Portent feature. While players may be able to manipulate the initial roll under certain circumstances, the vorpal roll will keep the dice honest.

Your campaign should be enjoying Victorian-levels of head rolling in no time.

2 thoughts on “Vorpal Sword Mechanics

  1. The Dex Save mechanic (made by your opponent) seems like a natural fit (if one is looking to tone down the lethality of vorpal weapons) for the following reasons:
    1. Re-uses familiar mechanic rather than inventing a new rule.
    2. Makes agile creatures harder to decapitate than slow lumbering ones (seems reasonable).
    3. Gives the DM a roll to determine whether it instantly kills opponent or not.
    4. Gives the Player a roll to determine whether their character lives or not (when being attacked by one).
    5. Allows a variable DC as a target based on each individual situation as adjudicated by the DM.


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