D&D 5E Great Weapon Master

[fuindordm]

OK, so I just did a quick analysis of the feat and the results are actually kind of interesting. I'm not taking into account the possibility that you can mitigate the -5 penalty with advantage.

Call P = your probability of hitting with a single attack
Call W = your average weapon damage with a single attack.

Then without GWF your expected damage is P * W
And with GWF your expected damage is (P - 0.25) * (W + 10)

After a little algebra you can find that the line of equality is P = 0.25 + W/40.

If you draw a graph with P = [0,1] on the y-axis and W = [0,20] on the x-axis, this line divides the area neatly in half, along a shallow diagonal. The area above the line is where GWF is better than a normal attack in terms of expected damage.

1. If your chance of hitting is low then GWF is seldom worth doing. For example, if you have even a slight disadvantage (P<=0.4), GWF only makes sense if W <= 6, which is pretty unlikely for a 2H weapon. Maybe you should consider it if a shadow drained your strength, but even then you should probably prefer increasing your odds of hitting at all over increasing expected damage.

2. If your chance of hitting is high (P>0.5) then GWF is usually worth it. But the higher your average weapon damage, the narrower the window. For example, if W=20 (+2 two-handed weapon, Enlarge, and potion of storm giant strength) then GWF is beneficial only if your chance of hitting without it is 75% (P=0.75).

I think it is really interesting that the higher you push W, the less useful GWF becomes. It's sweet spot is really in the range W=[5,15], when it is a good strategy at least half the time but not a good strategy against opponents that are already moderately difficult to hit. For W much higher than this range, the probabilities push GWF to a corner case where if you're sure to hit them anyway, you might as well hit them harder.

 

[sidonunspa]

Which is why in the game I'm playing in the GWM Paladin always delays till after I, the sword and board fighter with shield mastery, goes...

I get my chance to knock them down, if successful I then get my attack at Advantage...

then the paladin unloads with a -5 to hit, but attacks with Advantage... boom....

 

[Paraxis]

Which is why in the game I'm playing in the GWM Paladin always delays till after I, the sword and board fighter with shield mastery, goes...

I get my chance to knock them down, if successful I then get my attack at Advantage...

then the paladin unloads with a -5 to hit, but attacks with Advantage... boom....

There are plenty of ways to get advantage and when you have it GWF is well worth using IMO, but just so you know the above is not supported by the rules as there is no "Delay" in 5th edition, you go on your initiative or you ready an action, if the fighter readies his action to attack the enemy once he is knocked down, two issues come up.

First you might not succeed in knocking the enemy down so the triggering event never happens, but he could bypass this to ready his action to attack when you have finished attacking. Second, multiattack only applies on your turn so if the fighter normally gets two or more attacks with his attack action this is a bad idea since the readied action will be just a single attack.

 

[Prism]

Which is why in the game I'm playing in the GWM Paladin always delays till after I, the sword and board fighter with shield mastery, goes...

I get my chance to knock them down, if successful I then get my attack at Advantage...

then the paladin unloads with a -5 to hit, but attacks with Advantage... boom....

Surely a paladin attacking a prone opponent is against the rules? ;-)

 

[sidonunspa]

Even if you don't play with delay (which was an odd omission from the system) it's still a good strategy

And things get dumb once I hit 4th and get sentinel, any attack of opportunity will be a shove, and if I connect they are on their buts with 0 movement till their next turn.

:::evil giggle:::

 

[Paraxis]

Just double checked and an opportunity attack can not be a shove or grapple both state "using the Attack action", so it seems you can only do those things on your turn. An attack of opportunity is just a regular attack for damage.

 

[sidonunspa]

Just double checked and an opportunity attack can not be a shove or grapple both state "using the Attack action", so it seems you can only do those things on your turn. An attack of opportunity is just a regular attack for damage.

unless I'm using the battle master trip attack ability

 

[Coredump]

You should be more accurate. You do less damage against AC 22. Not all the time. AC 22 is a rare AC to say the least.

I was extremely accurate, I explicitly stated this was against AC22; I never said you do less damage all of the time.

While AC22 may be rare I used it because *you* brought it up in an attempt to show how 'broken' the -5/+10 was that it was still "easy" to use against AC22.
I was simply using your choice to show that your conclusion was false.

My experience is the fighter in our group uses it all the time save versus the Legendary, end game creatures. It is a big damage boost. So just analyzing it for AC 22 isn't telling the whole story. Even with a 25 str and +3 greatsword doing 22 damage, +10 damage is a 45% raw damage increase that boosts damage the lower the AC gets. That is a huge damage boost. If you could boost each of your hits by 45%, wouldn't you do it?

And again, your 'analysis' completely glosses over the number of attacks that will get *0* damage from missing. Depending on the AC, that -5 to hit can drastically counterbalance the +10 damage.

In our group the fighter uses it nearly every encounter when ACs are in the 14 to 16 range, a quite common AC. He's only level 10. Great Weapon Master is a big deal. It allows the martials to spike damage more than any other class.

Okay, lets again assume Str 20, GWF and GWM, and a +1 GS. +9 to hit against AC 15
Std dmg: 11.16
GWM dmg: 12.58

So congrats, the fighter is managing a 12.7% boost to damage. Thats kinda handy, but broken...???
In contrast, the GWF fighting style gives that same fighter a 10.7% boost.
Casting Bless gives about a 16% boost
etc

Does your analysis take into account how it interacts with abilities like Feinting Attack or Oath of Enmity? Those abilities martials use on the Legendary Creatures with higher ACs to use Great Weapon Master effectively. So martials use Great Weapon Master easily on trash with lower ACs and use it on Legendary Creatures with special abilities. Math analysis doesn't do how easy it is to use justice. Then there is even the occasional use of Inspiration or Bardic Inspiration that can boost hit chances as well.

I dont see a 10-15% boost as making lower AC monsters become 'easy'. But yes, it should be no surprise that when you start expending resources (inspiration, spells, Vows, etc) the fighter gets more effective. I am pretty sure that is how they are intended to work.

But sure, lets go look at your example, and lets assume he also has advantage against the dragon:
std dmg: 17.5
GWM dmg: 20.6
For a mind blowing 17.6% boost in damage.... of course, the reality is a difference of 3 hp per attack, against a creature with *487* hps..... I guess GWM just puts the game on EZ-mode...

 

[Celtavian]

And again, your 'analysis' completely glosses over the number of attacks that will get *0* damage from missing. Depending on the AC, that -5 to hit can drastically counterbalance the +10 damage.

Okay, lets again assume Str 20, GWF and GWM, and a +1 GS. +9 to hit against AC 15
Std dmg: 11.16
GWM dmg: 12.58

And your analysis completely glosses over people that aren't using a heavy weapon. It's comparing Great Weapon use with or without Great Weapon Master. You completely ignore that fact that those without a great weapon or two-handed fighting don't have any means to boost their damage.

So congrats, the fighter is managing a 12.7% boost to damage. Thats kinda handy, but broken...???
In contrast, the GWF fighting style gives that same fighter a 10.7% boost.
Casting Bless gives about a 16% boost
etc

12.7% boost without any buffs. That is a huge boost without buffs. Now imagine it against a one handed weapon fighter or even a two-weapon guy. Don't forget to take into account the bonus attack for dropping a creature or critting with Great Weapon Mastery.

I dont see a 10-15% boost as making lower AC monsters become 'easy'. But yes, it should be no surprise that when you start expending resources (inspiration, spells, Vows, etc) the fighter gets more effective. I am pretty sure that is how they are intended to work.

No other class has the means to become more effective. They don't have a -5/+10 boosting feat. Only ranged users and heavy/versatile weapon users have it. So how does everyone else become more effective? Are you ignoring that others don't have to means to gain even this boost?

But sure, lets go look at your example, and lets assume he also has advantage against the dragon:
std dmg: 17.5
GWM dmg: 20.6
For a mind blowing 17.6% boost in damage.... of course, the reality is a difference of 3 hp per attack, against a creature with *487* hps..... I guess GWM just puts the game on EZ-mode...

An 18% boost in this game isn't a big deal? Sorry, it is. No one else gets it. 3 hp per attack? Action Surge and it is 18 points. I'll tell you something, the chances that he'll roll much higher within the time frame of an Action Surge and a fight is pretty high, especially adding in reroll 1s and 2s from Great Weapon Fighting.

Why don't you play with the math over say a 100 hits. 3 points now becomes 300 more damage than anyone else that doesn't have Great Weapon Master.

Then start comparing it non-great weapon users. And casters using cantrips or save spells. And rogues using Sneak Attack. Compare to all of that. Let's see the differences.

Great Weapon Master may seem like a small boost to you. It's a huge boost compared to all other options save for ranged attacks with Sharpshooter.

10 to 18% more damage definitely kills things a lot faster.

 

[Staffan]

Yes, if you want to deal a lot of damage, you get Great Weapon Master. That's what it's there for. Others may want more defense, and go for Shield Master, which give a bonus action to shove people around, +2 or more vs targeted Dex save spells, and almost-Evasion. Or Mage Slayer, making you a nightmare against casters. Or Heavy Armor Master, reducing the damage of 80% or more of all attacks by 3 as well as getting +1 Strength.

Or for that matter, increasing your Strength from 18 to 20 - that's about a 10-20% damage increase in most cases (assuming no other bonuses to keep things simple, and that you normally hit about 60% of the time for 2d6+4 damage and instead hit 65% of the time for 2d6+5). Of course, that maxes out at 20, but that's what Great Weapon Mastery is for - turning it up to 11.