Ah, so his AC should have been 19, which means GWM would have been even less effective.
I believe you. I really do. But here is the deal... he got lucky. He needed a 13 to hit, and rolled it 5 out 6 times. Even with precision attack, he should have hit 3, maybe 4, times.
So yes, if you get really lucky, you can do a lot of damage. But the next round, without Action Surge and without being really lucky... you are talking less than 30 more hp. Heck if he got as unlucky in round 2 as he got lucky in round 1.... maybe no HP. Luck is a factor in this game.
First, I'm not going to continue this "Let's see who can look cooler" tossing out math and making quips at the other person. That isn't productive in a discussion like this.
I'll take one more shot at trying to explain some of the reasons why GWF and Sharpshooter work like they do for groups that optimize.
Maybe if we fought the dragon 10 times or a 100 times, the averages for the math would bear out. The average numbers are listed because it is assumed they will occur if rolling over a long period of time. That is how averages work. If you're rolling six attacks in a round, the averages won't necessarily apply. You'll get a bunch of random rolls with wide variation. You would have to generate the rolls over a long period of time to see how many rolls on average it took to get the average dice rolls. That's why I only show how much each hit does. The +10 damage from both feats is static and does not change based on the damage roll. It is a static +10 increase to an individual hit which on average increases damage absent other additions like magical weapon dice damage or crits by about 80%.
My buddy did it like this. I'll give you an example of a round before Reckless. Once he picked up Reckless, he pretty much used GWF at will. It was rare he didn't. A barbarian3/battlemaster fighter 11 using Reckless does an insane amount of damage. You run that some time. Tell me how that looks while he's taking half-damage with Bear Totem from everything while dealing out a load of damage. Pretty a much a winning combination and nightmare for the DM vastly overshadowing what other martials can do.
Let's focus on the level 11 battlemaster at the moment. He attacks the AC 19 dragon. Flies in, unloads Action Surge.
You tell me, does the following look like an amazing round of rolls?
18 str. +4. +4 proficiency. +1 sword. +9 to hit-5 =+4 to hit.
Six attacks. 1d20+1d4 each attack. He used a 1d10
1. D20 rolls 8. D4 rolls 3. 11+4=15. Miss. Use Superiority Dice: 1d10 rolls 5. 20. Hit.
2. D20 rolls 11. D4 rolls 2. 13 +4 17. Miss. Use Superiority Dice. 1d10 rolls 3. 20 hit.
3. D20 rolls 16. D4 rolls 1. 17 +4 = 21. Hit. Do not use Superiority Dice.
4. D20 rolls 3. D 4 rolls 1. 4 +4 = 8. Miss. Margin too large. Do not use Superiority Dice.
5. D20 Rolls 7. D 4 rolls 4. 11+4= 15. Miss. Use Superiority Dice. Rolls 8. 23 Hit.
6. D20 Rolls. 17. D4 rolls 2. 19 +4 = 23. Hit. Do not use Superiority Dice.
Five hits. Three of five superiority dice used. Still has two superiority dice next round. A bardic Inspiration Dice. And his Inspiration for advantage.
D20 rolls: 8, 11, 16, 3, 7, 17. Does that look out of whack as possible rolls to you?
d4 rolls. 3, 2, 1, 1, 4, 2. Does that look like out of whack as possible
bless rolls to you?
Superiority d10 dice rolls: 5, 2, 8. Does that look like out of whack superiority dice rolls?
That's all he needed to roll to hit 5 of 6 times for an average of 22 per hit for 108 average damage. He did 115, 7 over average in that round with lucky rolling. Does that seem like something uncommon in the game to you?
That's why the white room math doesn't work very well. He rolls 6d20s, 6d4s, and 3d10s. He rolled very different numbers. The averages come out over time, sure. But round to round finite combats, the averages vary considerably. That is how D&D fights occur. The ACs vary greatly, so you could in a night have all your bad rounds against trash creatures with lower ACs and still rarely miss. You could have all your good rounds against powerful creatures cheering why you do it. Or vice versa. Or a bunch of really average rounds which still leads to a lot of damage.
The hit points of a creature is a finite number. Creature hit points create the pool of damage that must be eliminated to defeat the creature. That means there is a premium on feats or abilities that allow you to do what we gamers refer to as nova or burst damage. Classes like the fighter with Action Surge or Paladin with Smite are extremely good at nova damage. Feats like Sharpshooter and GWF are especially effective for fighter nova damage with Action Surge due to the multiplicative effect. A barbarian is pretty good with GWF or a ranger with Sharpshooter, but a fighter can use these feats best. Either way the feats allow more upfront damage when using nova abilities like Action Surge or Vow of Enmity. If you are able to take a large portion of the hit points of the creature in the opening round, you don't leave sufficient hit points for the rest of the party to close the damage gap to get the average numbers. This is how most of the major fights go.
If you incorporate all the trash fights, you still see the skewing of damage but for different reasons. The paladin generally doesn't spend spell slots to smite trash. If he's fighting the guards at the gate, he won't spend precious spell slots to smite them down. The GWF might not even use GWF on every hit. He may use it on the gate guard with the 14 AC, but not on the gate guard with the 18. He makes his choice based on opponent AC rather than resource preservation. GWF and Sharpshooter are an unlimited resource. The wizard and cleric are also preserving resources because they will need spell slots for buffing in the major fights. The bard gets a lot of bang for the buck keeping up
bless. Between the cleric and bard, keeping a 1st level
bless spell up for most combats is a fairly low cost, efficient use of resources that provides excellent offense and defense. The damage still skews in favor of the GWF or Sharpshooter because they don't need to preserve GWF or Sharpshooter for big battle whereas the Paladin is saving his Vow and spell slots for smites for big fights. The wizard might drop an occasional
fireball, but he too is saving slots for possibly countering spells, buffing the party or himself, or using a powerful effect spell against a more formidable enemy. The fighter just keeps on swinging with GWF or shooting with Sharpshooter looking at the others saying, "I can do this all day."
During actual play you have players making intelligent decisions based on in game circumstances when it is best to use their abilities. GWF and Sharpshooter are easy to build around because they give a substantial damage advantage in a large number of circumstances with a limitless resource. It shows up as a substantial difference in damage between those with the feats and those without throughout an adventure. Analyzing anything beyond the static difference in potential damage per hit is far too difficult given the reasons the damage skews in favor of users of the feats. If you understand the underlying advantages of both feats like the static damage bonus and limitless resource advantage, its easy to see why in actual play they provide such a huge damage bonus and why efficient parties of optimizers like to build around them.
