Armor Piercer: A Homebrew Feat

 I've made monsters, I've made subclasses, and I've made spells. But I've never tried my hand at a feat.

I was writing recently about how modern and futuristic firearms struggle to keep up with the magic weapons that they are said to be equivalent to in the DMG. While the ability to have a +2 or +3 bonus to hit and damage certainly has some impact, the main difference, I think, is that certain ranged weapons have feats that can significantly boost their damage output. These feats, though, only really affect a small number of ranged weapons: Crossbow Expert is required to use Extra Attack with any crossbow-type weapon, but it also allows you to truly dual-wield Hand Crossbows and also effectively get the Two Weapon Fighting style with them. Great Weapon Master, while primarily designed for melee weapons, will also give a big boost to two specific ranged weapons, the Heavy Crossbow and the Longbow.

But no firearms benefit from either of these feats. Aside from the Piercer feat (which does boost their damage somewhat, but I'd guess far less) there's really not much you can do as far as feats are concerned to give you a good bump in damage. As a result, other than the Antimatter Rifle (which does insane damage, feat or no,) no Firearms outpace the Hand or Heavy Crossbow that is powered up with these feats and magic enhancement.

Can we fix that with a new feat?

Well, let's start on the conceptual level:

The rise of firearms, historically, was largely due to the way that they could pierce heavy armor. This was also true of other ranged weapons, like crossbows and longbows (the longbow, if it were historically accurate, ought to require a strength minimum because an actual medieval longbow had a 100-pound draw weight - pulling it back to fire was like lifting a 100-pound weight, so archers were insanely jacked.) But firearms gave you such an effect with all the power of the shot coming from the chemical reaction, no real muscle strength required.

Indeed, a lot of weapons from that era were designed to pierce armor. Before this technological development, the nobility and royalty did get into fights on the battlefield, because a full set of plate armor made you nearly invincible - like wearing shields all over your body. But a longbow, crossbow, musket ball, or the spike on a halberd or war hammer or on a morning star could get through that armor and actually injure or kill you. The plate couldn't be too thick or you wouldn't be able to move because it was so heavy, and it did fine against most blades, because those are relying on the sharpness and slashing action, which doesn't work very well against even a thin piece of steel.

Now, how should we represent piercing armor in D&D?

My first instinct was to do something like treat a target's AC as lower if it was relying on armor - like maybe something along the lines of "when you attack a creature, treat its AC as 10 + the creature's Dexterity if this value is lower than its regular AC." And honestly, I don't hate that design: it would make it very effective against monsters wearing actual armor, like a Death Knight, or against creatures with natural shells or plates like a Chuul.

It's also quite variable in effectiveness, and forces your DM to make a calculation with every monster you attack, which could be tedious.

Instead, I think we take some existing technology: the Graze mastery.

Indeed, I actually thought this with a different scenario in mind: while in real life a shotgun's blast is a much tighter grouping than we see in video games, the principle is the same: you shoot out a spread of, er, shot, covering a wider area and thus having a better chance of hitting your target. And Graze could very easily represent winging a foe, with only some of the blast actually hitting them.

But this can also, I think, represent a bullet or spike hitting a foe's armor, which absorbs part of the impact, but still piercing through to deal some damage.

Graze, as a mastery, is only found on the Greatsword and the Glaive, both heavy melee weapons that deal slashing damage. Graze is also, probably, the best weapon mastery for damage output.

I'd initially intended this feat to only benefit firearms, but I think you could make a solid argument that it can work with any of the weapons that were designed to pierce armor. And so, I think I'm going to let it apply to any martial weapon that can deal piercing or bludgeoning damage. They should be martial weapons: I don't think a Dagger or a Club ought to benefit from this. But the following weapons would gain this benefit if we used the aforementioned parameters:

Flail, Lance, Maul, Morningstar, Pike, Rapier, Shortsword, Trident, Warhammer, War Pick, Blowgun, Hand Crossbow, Heavy Crossbow, Longbow, Musket, Pistol, Semiautomatic Pistol, Automatic Rifle, Revolver, Shotgun, Hunting Rifle.

I think you could argue that we ought to include the Halberd, and that the Rapier, Shortsword, Blowgun, and Hand Crossbow don't quite fit this.

But I think I'd prefer to use these broader identifiers to ensure that modern firearms were being included in a player-facing option.

The feat also does involve weapon masteries, which not every class gets (including Artificers, which I find frustrating). I think we might thus make it a prerequisite:

    Armor Piercer:

General Feat (Prerequisite: Level 4+, The Weapon Mastery feature or the Weapon Master feat, proficiency with a martial weapon)

You gain the following benefits.

Ability Score Increase: Increase your Strength or Dexterity score by 1, to a maximum of 20.

Mastery Switch: When you attack with a martial weapon that deals piercing or bludgeoning damage whose mastery you can use, you can replace that property with the Graze mastery for that attack.

    The structure of this feat simply replicates a more limited version of the Fighter's Tactical Master feature. I think this would probably wind up being decent, but how much does the feat actually add, damage-wise, for our weapons? See, if used on a Maul, for example, all this does is let us treat the Maul like a Greatsword, which feels probably too thin as a feat on its own.

If we revisit the post looking at modern and advanced firearms (as you notice, this doesn't do anything for futuristic guns) we saw that all the modern firearms were lagging behind +2 versions of the Hand and Heavy Crossbows that had enabling feats.

Before we add any damage to the feat, let's see how they do now. I was going to just use our old values, but the AC of 15 was so marginal that I worry it might have been a kind of skewed result.

Instead, we'll look at an AC of 20, but with the same assumptions: A Fighter with 20 Dexterity and the Archery fighting style. Using a pair of +2 Hand Crossbows with Crossbow Expert to get three attacks, using a +2 Heavy Crossbow with Crossbow Expert (just to use extra attack) and Great Weapon Master, and now using our mk. 1 Armor Piercer feat.

I acknowledge that by raising the AC, I'm making Graze more valuable, but let's just try it.

    +2 Hand Crossbows:

Given we're doing fewer calculations, let's see if we can account for Vex.

We deal 1d6+7 damage on a hit, and an extra 1d6 on a crit (so 10.5 and 3.5)

We have a +13 to hit. Without advantage, we've got a 70% chance to hit.

10.5x70%, or 7.35, plus .175, so 7.525 on an attack without advantage.

If we have advantage, the chances become 91% chance to hit, and 9.75% chance to crit.

So, 10.5x91%, or 9.555, plus 3.5x9.75%, or .34125, so 9.89625 damage on an attack with advantage.

First attack (assuming no external advantage) is 7.525.

Second attack has a 70% chance to have advantage and a 30% chance to be made straight, so 7.525x70% is 5.2675 and 30%x9.89625 is 2.968875, so our average damage on the second attack is 8.236375 (and yeah, we can probably round off to the nearest tenth of a damage point, but hey, precision!)

So, how likely are we to have advantage on the third attack? It depends on whether we hit on the second attack. And the likelihood of that is dependent on whether we hit on the first attack. We have the following scenarios that grant advantage:

First attack hits, second attack hits. 70% (first attack) x 91% (second attack) for 63.7% of the time.

First attack misses, but second attack hits: 30% (first attack) x 70% (second attack) for 21% of the time.

Add these together and that's 84.7% of the time that we get advantage on the third attack.

So! (dear lord):

Third Attack: 9.89625x84.7% is 8.38 (ish, we can just round) plus 7.525x15.3%, or 1.15, so our third attack is going to do 9.53

Giving us a total damage of 25.29! (I promise no more Vex for this post).

    +2 Heavy Crossbow

Same 70% hit chance. 1d10+11 on a hit, or 16.5, and 5.5 extra on a crit.

16.5x70% is 11.55, plus 5.5x5% is .275, so our total per attack is 11.825. With two attacks, that's 23.65.

    Shotgun:

I'm picking the shotgun one of three modern firearms that have the same and medium damage potential. This math will work just as well for Revolvers and Automatic Rifles (though ignoring Burst Fire). Note that the Semiautomatic Pistol gets Vex, but we're mainly trying to see if this feat will let these weapons keep up.

Because Graze lets us add our damage modifier on a miss, we can actually just ignore it and add it at the end (there's a 100% chance that we get to deal that much damage, and it doesn't increase on a crit).

We only have a +11 to hit, so we're going to have a 70% hit chance. Because we can just look at the damage of the dice, we can actually just fold the 5% crit chance into the same amount. These are 2d8 weapons, so they deal 9 damage on average.

9x75% is 6.75. We add back in that guaranteed 5 to give us 11.75 damage per attack, doubled to get 23.5, which is now very nearly caught up with the Heavy Crossbow.

The Hunting Rifle does 2d10, so 11 damage on average. 11x75% is 8.25, and adding in the 5 we get 13.25, or 26.5 with the two attacks.

    So, that's interesting: I do think this feat manages to kind of solve the problem, giving modern firearms parity with equivalent magic items.

That being said, it feels weird, to say the least, that the damage boost is simply coming from swapping out for a different mastery.

To be sure, some of the weapons included here are also going to benefit a lot from Graze - Graze only natively comes on heavy, two-handed weapons, so getting it on a one-handed weapon like a War Pick (a weapon absolutely designed in the real world to pierce armor) is going to be a big deal. I actually think, proportionately, it'll be a bigger deal than it would be for a firearm with a large die pool, because more of your damage with a weapon like this is going to come from your modifier.

Arguably, the weapon that best benefits from this is a Blowgun, where all but 1 point of its damage comes from your Dexterity, so Graze is nearly like saying "you cannot miss."

But when you could just as easily trade out your Maul for a Greatsword or your Pike or Lance for a Glaive, does this feat feel kind of underwhelming? It does. Is that a problem? Maybe? I mean, there are plenty of feats that are going to feel more impressive on some weapons more than others. Much as Great Weapon Master does technically benefit non-heavy weapons but obviously does better with heavy weapons.

And yet... I don't know, it feels thin.

The benefit of the current design is that it will work even in a campaign that doesn't have modern firearms. That said, while Graze is certainly a better mastery than just about any other except perhaps Vex and Nick, this feat does force you to give up those other masteries to use it, at least in the moment.

So perhaps there's a narrower, more specific feat we could apply.

I do still find the Graze mastery, or at least its equivalent functionality, to be a pretty elegant way to reflect the armor-piercing capabilities of gunpowder weapons. Perhaps, then, we could roll this into other benefits.

Let's give it a shot, so to speak:

    Deadeye

General Feat (requires level 4+, Dexterity 13+)

Ability Score Improvement: Your Dexterity score increases by 1, to a maximum of 20

Deadly Shots: When you make an attack roll with a Pistol, Musket, or any ranged weapon with the Reload property, and you miss, you can deal an amount of the weapon's damage type equal to the ability modifier with which you used to the attack to the target.

Quick Reload: You ignore the Loading property of Pistols and Muskets, and you can reload a ranged weapon with the reload property using your object interaction oncer per turn.

    Yeah, I kind of like this. It doesn't require you to give anything away, meaning you'll still have your given mastery.