@DND_Reborn - what are your goals in creating your new Fighter class? Let's get as explicit as possible.
Certainly, glad to do it!
Do you want to increase their damage. If so, at what levels and by how much.
Not really. If changes up their damage slightly, that is fine, but that isn't a goal.
Now, changing their versatility is an issue. I think adding some BM maneuvers (a few) is a good place to start, but many of them just result in more damage so isn't ideal for me.
A better change, but would be somewhat build specific, would be gaining advantage when knocking a creature prone. This way, it doesn't directly impact damage, but it makes the shove/knock prone attack more interesting and beneficial over "just causing more damage". I know it
can help damage, but not directly.
Do you want to increase their Nova capabilities. If so, at what levels and by how much.
Somewhat, but not Nova so much as a way to make a huge, game-changing impact on an encounter. This would be a bit in tier 3, but more so in tier 4. The purpose is to bridge that cap with what high level casters are capable of. Personally, this isn't an issue
for me, but for others and I am just trying to help build a class that helps them out.
Do you want to increase their out of combat abilities. If so, at what levels and by how much.
This
was a goal, until I took a deeper look into the feats just in the PHB alone. Those extra ASIs at 6th and 14th could go a good way towards making a fighter more effective in the exploration and social pillars, without necessarily stepping on the toes of the skill monkeys (bards and rogues with expertise).
The problem is most players feel to stay competitive in combat, those ASIs have to be used in abilities or for feats to make them better at combat; instead of choosing feats that would help outside of combat.
So, while I am not adverse to this, it really isn't a major goal anymore. A feature like Many Leagues, which would give fighters some exploration or social skills, would alleviate the issue and allow them to still use the ASIs for combat...
Do you want to increase their defensive capabilities. If so, at what levels and by how much.
Not so much really. If anything, just having Indomitable be a success instead of a reroll, and maybe give Fighters an extra save or two (Fighters in AD&D had the best saves by the end...) would be good.
Finally, while I don't feel niche protection must be absolute, I do think having a good part of it back in the game is preferable. Too many classes are good at combat, where the Fighters should be best IMO, but in the same respects too many classes and subclasses get magic now, which isn't a good design choice IMO, but I know most people seem to like it.
Oh, one last thing, I would like to keep it as close to the RAW class / progression as possible. So, the big places to add something would be levels 6 and 14 to replace the bonus ASIs, and then 13 and 17 where right now they just get more uses of features instead of new features.
Just FYI, I'll be busy tomorrow, so I might be a while in replying. Cheers and thanks for any input/assistance!