D&D 5E When to turn on Great Weapon Master

[UngeheuerLich]

There is more than average damage indeed. But there are damage treshomds and overkill too. And sometimes it is just a gamble.
In statistics there is the law of big numbers. If you have a lot of attack rolls, average damage is meaningful. If you only have a few attacks, reliability may be more useful.

Just look at the extreme (impossible) cases: 100% hit chance, 1 damage. You are killing steadily. If you only hit on a 20 but kill the target with every hit, on average your 20th attack kills the target (that is mathematical fact). So if the target has 20 hp, both options will be equal on average... but for every single fight it is totally different. While you are sure that you kill the monster after 20 hits with the first method, the monster can be dead after a single attack with the other or can stand for 40 rounds or more. Unlikely but possible. The tragic part is: when you miss 10 times in a row with the secon method, on average you still need 20 more rounds since your average chance to hit is still only 5%. 2 Attacks and advantage shortens it to 5 rounds... still a lot of time.

 

[shoak1]

Your math is focused on average damage. That is only a small part of the equation.

How many hps does the enemy have? Are there 'on hit' benefits that come with hitting such as knocking prone with Fellhanded? Is there an offesting benefit on a miss (damage on a miss)? How much damage can an enemy do if I do not take it down this round before it can go?

Understanding the math gives you a good tool, but is only one of many tools that you need to consider when evaluating options like GWM.

I addressed how many hp a creature has so....don't think you read my whole post.

As or your other particular special scenarios, so what? It does not invalidate my analysis to bring up "what if a unicorn attacks you w/stunning fist?". In most situations, the guide will serve a player well.

 

[shoak1]

There is more than average damage indeed. But there are damage treshomds and overkill too. And sometimes it is just a gamble.
In statistics there is the law of big numbers. If you have a lot of attack rolls, average damage is meaningful. If you only have a few attacks, reliability may be more useful.

Just look at the extreme (impossible) cases: 100% hit chance, 1 damage. You are killing steadily. If you only hit on a 20 but kill the target with every hit, on average your 20th attack kills the target (that is mathematical fact). So if the target has 20 hp, both options will be equal on average... but for every single fight it is totally different. While you are sure that you kill the monster after 20 hits with the first method, the monster can be dead after a single attack with the other or can stand for 40 rounds or more. Unlikely but possible. The tragic part is: when you miss 10 times in a row with the secon method, on average you still need 20 more rounds since your average chance to hit is still only 5%. 2 Attacks and advantage shortens it to 5 rounds... still a lot of time.

Look, overkill is occassionally gonna shave off a few points but it does not really change the situation much since then it may provide a free bonus attack because you dropped a creature.

Your extreme cases are really just theoretical, not real world. And no, each fight's hp/damage amounts are not "totally different" - there is an expectation in D and D of level appropriate content - and that means monsters that can handle several swings of your axe, but not 20 swings or 1 swing lol.....but I will remember your point the next time I pick GWM for a hero doing 1 damage per round lol and facing a 20 hp mob...

Its almost like you are saying "if every last detail and scenario cannot be determined about a situation/thing than there is no use doing any analysis on it." I know there are a lot of you artsy RPGers out there that see science/math/facts as subjective rather than objective, but come on....

 

[shoak1]

I realize you're trying to offer a simple guideline to using GWM, but really all you're doing is illustrating why it is such a headache.

Really how is it a headache? You have a fixed number that is unchanging until you level or get a different melee weapon.

So my barbarian turns it on when he needs a 10 or less to hit. Simple. You dont need to recalculate every fight, unless you damage buff - then subtract 1/2 the buff. Done.

 

[UngeheuerLich]

... lot of you artsy RPGers out there that see science/math/facts as subjective rather than objective, but come on....

Hey, i don´t know what you mean by artsy RPGler... but i certainly don´t see math as subjective... actually I have a university degree in math and know how to apply it properly. That i something I am missing here with a lot of posters. Just because you can do basic math it does not mean you know how it works.
If you don´t understand why I used the extreme cases to illustrate the problem of statistics then I really can´t help you.

I mean, play as you wish and do your calculations in a white room... but that is not mathematical truth. Just because the average damage is higher does not mean it is better. Law of big numbers is a thing. Gamer´s fallacy too.

edit: or look under "volatility" or "standard deviation" or "variance" all useful things to consider besides average damage.

 

[shoak1]

If you don´t understand why I used the extreme cases to illustrate the problem of statistics then I really can´t help you. I mean, play as you wish and do your calculations in a white room... but that is not mathematical truth. Just because the average damage is higher does not mean it is better. Law of big numbers is a thing. Gamer´s fallacy too.

The typical PC using GWM is going to be deciding on its use approximately 2-6 times per fight and 30 or so times per level. He is going to start off doing 9+ damage per round and eventually do up to 15 dmg per round without GWM. The monsters he fights are gonna typically have dozens of hp. Those are the facts. Now let's look at your post again:

If you have a lot of attack rolls, average damage is meaningful. If you only have a few attacks, reliability may be more useful....Just look at the extreme (impossible) cases: 100% hit chance, 1 damage. You are killing steadily. If you only hit on a 20 but kill the target with every hit, on average your 20th attack kills the target (that is mathematical fact). So if the target has 20 hp, both options will be equal on average... but for every single fight it is totally different. While you are sure that you kill the monster after 20 hits with the first method, the monster can be dead after a single attack with the other or can stand for 40 rounds or more. Unlikely but possible. The tragic part is: when you miss 10 times in a row with the secon method, on average you still need 20 more rounds since your average chance to hit is still only 5%. 2 Attacks and advantage shortens it to 5 rounds... still a lot of time.

How does any of your extreme cases apply to the typical D and D player/PC using GWM? Who hits on a 100% chance? Who does only 1 damage? Who picks GWM then proceeds to only have "a few attacks" for the rest of his career? So why is any of your post useful to THIS subject?

You say yourself that if you have a lot of attack rolls than average damage is meaningful. And certainly anyone taking GWM in the "real" world is going to be making a lot of attack rolls. So maybe your post just a long-winded way of saying "good job shoak1" .....

 

[shoak1]

First things first - I like this approach. Straightforward, easy to implement at the table...How would you add in advantage, considering all of the barbarians with GWM? That both changes the chance to hit variably but also close to doubles chance for a crit. Is it possible to condense that to a nice rule-of-thumb like you have for the rest?

Thanks for the input. Advantage would subtract 4 from the target # I guess, because +4 seems to be the equivalent for advantage. As for the additional crit chance, it really does not change the target # since an additional 5% chance of +7 damage is only +0.35 extra damage and it takes 2 points of average damage to change the target #.

I'd like to modify this to "if you are likely to kill a creature with a hit AND NOT WITHOUT THE +10...". First if you'll kill without the +10 the extra damage is just wasted overkill for a lesser chance to hit. And second you don't need to be using the feat (or even wielding a heavy weapon, as long as it's a melee weapon) to get the bonus attack.

Great point, I will edit original post.

 

[UngeheuerLich]

... a long-winded way of saying "good job shoak1" .....

Most certainly not. Because it only presents half of the facts. What you calculated was good and right. Good job on that part. What you neglected was the other half.

 

[Sacrosanct]

Most certainly not. Because it only presents half of the facts. What you calculated was good and right. Good job on that part. What you neglected was the other half.

Yep. Math isn't subjective, but a pretty big chuck of RPG combat certainly is because it involves people who make decisions. Last time I checked, people don't play D&D in a computer arena where there are no other factors involved. And anytime you involve subjectivity into an equation, the WHOLE equation becomes subjective.

 

[UngeheuerLich]

Yep. Math isn't subjective, but a pretty big chuck of RPG combat certainly is because it involves people who make decisions. Last time I checked, people don't play D&D in a computer arena where there are no other factors involved. And anytime you involve subjectivity into an equation, the WHOLE equation becomes subjective.

It is even more. It is not as easy as 1+1=2 but we are talking about statistics. The important thing to know about statistic is that you can only make good calculation if you have more than a single attack roll. The more rolls you do, the better your estimations. And all those estimations are only correct if over all those rolls the conditions don't change. And then we are back on the thing you pointed out.
If for example you only hit with a 16 or more, even if the average damage would increase over 10 rounds, it is still a gamble each round. It is betting to toll a 4 on a d4 and only deal damage if you roll it. Even with advantage that will result in a lot of tounds where you don't hit.
And each round it is the same chance.
If you think your chance to hit increases if you didn't hit for a while that is gamer's fallacy.
So you point is important. You never stand toe to toe with an enemy and just trade hits. At least at our tables.