We're going to need the power of maths The balance of SS can be considered against melee (Great Weapon Master) and single-strike classes (Rogue). Let's use your and @ro's revision - thus SS applies only to the Attack action. I'll use a base 50% chance to hit, and please note that Archery improves as the attack chance reduces. All characters are assumed to have 18 in their relevant ability score.
Starting with Rogue, how much does SS cause Fighters to overshadow them at range?
By 11th level this picture looks much worse for Rogues.
SS allows Fighter to overshadow Rogue substantially more at ranged, given your an @ro's revision. I should add that characters have equal access to bonuses that change these numbers, like Half-Orc Savage Attacks. I'm just showing the base case. On the whole, such bonuses favour Archery and Extra Attacks.
Next look at Great Weapon Master
So we can see that Archery+SS Fighter with Longbow is overshadowing both Rogue and Great Weapon Master. At 600' range! The reason is essentially that a flat +2 add to attack chance scales powerfully. The worse the chance to hit, the better (relatively) it does. Great Weapon Master always goes in the opposite direction: the better the chance to hit, the better it does. If you apply any magical buffs to all this, Fighter goes off the chart compared to Rogue.
We have to reflect on why we want to have damage that equals the best seen in toe-to-toe - at long range (600')!? From range, basic balancing factors such as lower AC (from using a two-handed weapon) don't play as much of a part. From range, if movement speeds are equal the Archery Sharpshooter can kite - mitigating 100% of damage. Flip through the Monster Manual and we see that few foes are equipped to deal with that.
[Edited to give Rogue Heavy Crossbow, as they only make one attack anyway. Range will be shortened to 400'. Also fixed incorrect application of penalty to Extra Attacks under my revision.)
I agree with you there of course. The Rogue is compelling because of the mix of reasonable combat ability with reasonable social and first-class exploration abilities. That is why I wanted to show both the Rogue and the two-handed melee weapon Fighter for comparison. The Sharpshooter Archer with full benefit of Extra Attacks outclasses the former and matches the latter, but at 600' range! Up to this point we haven't attempted to put a value on that range.I'm not disputing your numbers, but I think in your examples you're looking at the big picture a bit wrong. First, I don't think the Rogue being unable to keep up with the fighter in raw damage is a problem. That's pretty much what the fighter does. The only thing the fighter does. He's a one trick pony. The Rogue on the other hand is a tool box with options and capabilities that extend far past combat. There is nothing wrong with letting the fighter be better here.
It's true that most characters manage to have advantage a lot of the time. Whenever a Sharpshooter or Great Weapon Master with Extra Attacks gains advantage, they go off the scale compared with Rogue. We'd hope the Rogue has advantage more often, but we can't forget that a Battlemaster with Archery can use Precision Attack, which is worth about the same as advantage and stacks another d10 onto their shot. And spells like Bless help Extra Attackers more than single-attackers. I kept things deliberately barebones because most of the adds push Sharpshooter Extra Attackers even further ahead of Sharpshooter single-attackers like Rogue.Second, I think you are discounting the effectiveness of advantage and at least in my experience, it is far easier and more common to gain advantage as a melee character than it is as a ranged. Just about every game I can think of in recent memory for us has had at least two melee characters and setting up flanking is not that difficult. There are also numerous effects that knock targets prone, giving advantage to melee and disadvantage to ranged. I'm sure there are more. I'm not sure if you were looking at advantage in your numbers, but it is often required for sneak attack.
I would agree with you that we could might - given plenty of time and playtesting - find a better mechanic. In part, my goals are to sustain existing content and minimise additions. One reason for that is smaller changes are more likely to be successful. Adding the words "Once per turn" is a conservative change. For single-attack characters, the feat works exactly as it did before! And for all characters the rest of the feat works unaltered. Additionally, the power attack is part of D&D's history. It's cherished because it speaks to a tradition, and because it gets players to make interesting choices. Is my foe nearly out anyway, or do I need this shot to hit as hard as possible? That said, a flat +proficiency to damage would pay off Extra Attacks even more than the current mechanism. One attack at +2 to +6 to damage will do less than three with that bonus on all of them.I understand your reasoning behind this and agree with you that ranged should not be outshining melee in combat. I just don't think you are going about it the right way. I'm still not a fan of a -5/+10 mechanic in general (+Prof to damage would be better imo), but you seem inclined to keep it there regardless so I'm playing along.
Just so you know where I landed.Does the +10 speed from Skulker overlap too much with the +10 speed from Mobile?
Why are you limiting Sharpshooter but not Great Weapon Master?
Just so you know where I landed.
For Agile I ended up keeping the speed increase. It looks to me like the risk of egregious consequences for stacking is minor, and there are several other cases of effects being duplicated across multiple feats. A speed increase elegantly handles the grab-bag of Athlete benefits, while supporting, rather than doing less for, the archetype that might most want it (Thief).
For Sharpshooter I conducted a lot more analysis and for me "Once per turn" is solid balance on the power-attack. It feels very close to exactly where ranged damage should be. And for characters with single-attacks, the feat works 100% as it always did.
That's not accurate. If you take a look at my survey, you should see that with the exception of CEx and SS I'm attending to feats that players aren't taking. Sadly, Rogues bear the brunt of under-performing feats.It seems to me that your favorite character type is Rogue/Thief. Most of your choices to modify feats seem to favor the melee rogue, whether avoiding letting others have expertise, or nerfing ranged combat, etc. If this is an accurate observation, I have a few thoughts.
No, I have no preference for Rogue. Ranger is the weakest PHB class, but that is a separate problem. Ranger isn't weak because of feats. In fact, feats can save a Ranger who is prepared to exploit them.You talk of the rogue as being a mix of combat and social with top-tier exploration abilities. How does this compare to a Ranger, who is more explicitly oriented toward exploration and also has decent combat options? How is your favoring of the Rogue impacting other character builds? The Ranger is often viewed as the weakest PHB class, and yet your proposed fixes seem to weaken the Ranger even more relative to the Rogue.
Is your preference for the Rogue resulting in arguments against things that would benefit other characters and coloring your perspective on balance?
I dislike expertise here for reasons outlined previously.
I liked the lateral thinking here: it got me thinking! I want to propose we merge Dungeon Delver with Skulker instead. What do you think?
Again your takes on these got me thinking. I want to propose merging only Keen Mind with Observant. Thoughts?
Healer is profoundly good just per RAW.
Mage Slayer is very tricky to get right! I've been discussing it with my players. We think the crux of Mage Slayer really needs to be a chance to interrupt the cast, because otherwise the mage simply mind controls the melee character, or Misty Steps away or whatever. So I have ninja-edited it with another version. Removing the save buff as you suggest.