So initially, my proposal for improving the Champion was to add +2 to damage in addition to their expanded crit range. For me, this made sure that the Champion consistently felt the usefulness of their ability, since theoretically even with an expanded crit range you could end up never landing a crit. I also felt that Remarkable Athlete could stack with proficiency. But now, I have a different idea.
I like your idea, but I'll add that in my own analysis of Champion vs. Battlemaster damage, Champion held its own just fine. My numbers are in contrast to [MENTION=57494]Xeviat[/MENTION]'s, likely due to different assumptions. IMO, there's absolutely no need to boost the Champion's damage. Damage-wise, it's well-designed and fine as is.
[SBLOCK=Fun with Maths]
Fighter: Champion vs. Battle Master DPR
Some players assert that Champion is weaker than Battle Master in terms of its damage output. Thus far, having seen both at my table playing up to 6th level, I didn't feel this was true. I ran some numbers, and it cast further doubt on that assertion. They seem practically evenly matched in terms of DPR.
Assume an average of 4 encounters of 4 rounds each
(16 rounds of combat total) per day, against a monster of CR equal to the party’s level. Also assume that the fighter can always attack each round (i.e. is in range and isn't paralyzed). Some days will have fewer or more encounters, some encounters will be over in a round while others will last a long time, and most assuredly there will be greater variety of CR and combat scenarios in actual play, but assume it’s a wash in the long-term.
I’m comparing a human fighter wielding a longsword one-handed, no feats, no magic items. Both have the Defense fighting style, but I’ve compared two versions of the 10th level+ Champion, one with bonus Dueling style and the other without. I’m comparing them at levels 5, 11, and 15.
Level 5
Str 18, AC 16 (scale mail, Dex 14), HP 44 (Con 14), longsword (2 attacks) +7 hit, 1d8+4 damage (8.5), 5% critical hit (battlemaster), 10% critical hit (champion), crit 2d8+4 (13)
Battlemaster superiority dice 4d8 (18), added only on hits
vs. CR 5 monster AC 15; 65% chance to hit
Attacks/day = 32
Critical hits (champion, 10%) = 1.6 ≈ 2
Critical hits (battlemaster, 5%) = 0.8 ≈ 1
DPR (champion) = [ (30 attacks/day * 0.65 chance to hit * 8.5 avg. damage) + (2 attacks/day are crits * 13 avg. damage) ] / 16 rounds = [ (165.75) + (26) ] / 16 =
11.98 DPR
DPR (battle master) = [ (31 attacks/day * 0.65 chance to hit * 8.5 avg. damage) + (1 attack/day is crit * 13 avg. damage) + (18 avg. damage superiority dice) ] / 16 = [ (171.27) + (13) + (18) ] / 16 =
12.64 DPR
Level 11
Str 20, AC 17 (half plate, Dex 14), HP 92 (Con 15), longsword (3 attacks) +9 hit, 1d8+5 damage (9.5) or 1d8+7 (11.5) champion, 5% critical hit (battlemaster), 10% critical hit (champion), crit 2d8+5 (14) or 2d8+7 (16) for champion
Battlemaster superiority dice 5d10 (27.5)
vs. CR 11 monster AC 17; 65% chance to hit
Attacks/day = 42
Critical hits (champion, 10%) = 4.2 ≈ 4
Critical hits (battlemaster, 5%) = 2.1 ≈ 2
DPR (champion, duelist style @10th) = [ (38 attacks/day * 0.65 chance to hit * 11.5 avg. damage) + (4 attacks/day are crits * 16 avg. damage) ] / 16 rounds = [ (284.05) + (64) ] / 16 =
21.75 DPR
DPR (champion, no duelist style @10th) = [ (38 attacks/day * 0.65 chance to hit * 9.5 avg. damage) + (4 attacks/day are crits * 14 avg. damage) ] / 16 rounds = [ (234.65) + (56) ] / 16 =
18.16 DPR
DPR (battlemaster) = [ (40 attacks/day * 0.65 chance to hit * 9.5 avg damage) + (2 attacks/day are crits * 14 avg. damage) + (27.5 avg. damage superiority dice) ] / 16 = [ (247) + (28) + (27.5) ] / 16 =
18.91 DPR
Level 15
Str 20, AC 17 (half plate, Dex 14), HP 128 (Con 16 @ level 12), longsword (3 attacks) +10 hit, 1d8+5 (9.5) damage or 1d8+7 (11.5) champion, 5% critical hit (battlemaster), 15% critical hit (champion), crit 2d8+5 (14) or 2d8+7 (16) for champion
Battlemaster superiority dice 6d10 (and always have 1d10 at the start of combat even when depleted), so if we assume battlemaster spends 3 superiority dice per encounter, then we should add 2 more effective dice given the assumption of net 4 encounters/day. 8d10 (44).
vs. CR 15 monster AC 18; 65% chance to hit
Attacks/day = 42
Critical hits (champion (15%) = 6.3 ≈ 6
Critical hits (battlemaster, 5%) = 2.1 ≈ 2
DPR (champion, duelist style @10th) = [ (36 attacks/day * 0.65 chance to hit * 11.5 avg. damage) + (6 attacks/day are crits * 16 avg. damage) ] / 16 = [ (269.1) + (96) ] / 16 =
22.82 DPR
DPR (champion, no duelist style @10th) = [ (36 attacks/day * 0.65 chance to hit * 9.5 avg. damage) + (6 attacks/day are crits * 14 avg. damage) ] / 16 = [ (222.3) + (84) ] / 16 =
19.14 DPR
DPR (battlemaster) = [ (40 attacks/day * 0.65 chance to hit * 9.5 avg. damage) + (2 attacks/day are crits * 14 avg. damage) + (44 avg. damage superiority dice) ] / 16 = [ (247) + (28) + (44) ] / 16 =
19.94 DPR
[/SBLOCK]
I'm considering at level 3 Improved Combat also allows the Champion fighter to use their bonus action for grapple, disarm, and shove attempts. This is similar to the Rogue's Cunning Action, giving the Champion fighter something to do with their bonus action if they don't use Two-Weapon Fighting.
Level 7 Remarkable Athlete stacks with proficiency.
Then At level 10, in addition to a second fighting style, a Champion adds half proficiency on any saving throws they aren't already proficient in.
Finally, at level 15, Superior Combat includes the following add-on: In addition, whenever you attempt an ability check using Strength, Dexterity, or Constitution, you can treat a d20 roll of 9 or lower as a 10.
I feel like these additions are not necessarily overpowering. It makes the Champion more strategic in greater options with their bonus actions (also synergizes with expanded crit), tougher (in their saves), more athletic (potential for 1.5 proficiency in Athletics/Acrobatics), and more successful in their athletics (by taking 10 with physical skills).
What are people's thoughts?
Not a fan of the bonus action shoving etc, since it marginalises TWF even further and duplicates a significant benefit of the Shield Master feat.
Overall, I think it's a move in the right direction. But what I see you trying to do are shore up flaws of the fighter core class (e.g. it should have better saves, Indomitable kinda sucks, & it should have a feature supporting increased versatility/creativity) using the Champion sub-class. Whether you want to address such issues in a subclass – when they're really issues with the core class – is questionable.
Your tweaks to Remarkable Athlete seem reasonable.
Replicating Reliable Talent might be a bit much. Reliable Talent feels unique to a skill monkey like the rogue. I could see maybe giving Reliable Talent to a certain bard subclass. But to a fighter? I don't know, it feels out of place.
I do agree with Cap'n Kobold, however, that the bonus action proviso to shove is especially questionable for fighters, who seem likely to be using bonus actions for extra attacks. You can have a two-weapon fighting rogue and leave the rogue with a choice between Cunning Action and an extra attack – that sort of choice makes sense for a rogue, who isn't "the best at fighting." However, a fighter IS "the best at fighting", so if you give the class an ability mirroring Cunning Action, I think you want to avoid requiring a bonus action; instead, I'd recommend reigning in the power (e.g. no grapple or disarm) but letting the fighter use it once per round, either during their turn or at the end of another creature's turn.
This gets back to my point about how rules supporting a reactive/adaptive play style lead to supporting a player's creativity in the heat of the game. For me, that's the spirit of an "old school fighter." Let me react with some crazy idea. *Definitely* don't tell me "well, you can't stow your bow, draw two weapons, then attack."
As for replicating a bit of Shield Master by allowing Shove...YMMV...personally, the benefit of a fighter creating more dynamic movement on the battlefield outweighs the cost of stealing some of a feat's thunder. If it's a real issue for you, but you like the idea of the fighter Shoving enemies around wily-nilly, I'd just replace that line of Shield Master with:
You can equip a shield as a bonus action, instead of an action.