MostlyHarmless42
Adventurer
My fix will be this:
1st level; Leave as is. It's a perfectly fine feature at this level and frankly at this point Hunter's Mark needs concentration in order to prevent multi-classing shenanigans.
Either 5th, 7th, or 9th level: They get a new feature that allows them to cast Hunter's Mark without concentration. It's still early enough that players will actually get to use it, but late enough that multi-class optimizers won't label it as a "must have". Additionally, the true competition for a ranger's concentration slot doesn't actually start until 2nd and 3rd level spells anyway. I'm leaning towards 5th or 7th level.
13th lvl: Grant the advantage to all attacks to a marked target HERE from the 17th level feature with Hunter's mark.
I might also possibly Increase the hunter's mark damage to 1d8 here as well for better scaling towards 20th level. This is the real part where that feature would actually feel good and it's not as potent as people think. Remember at this point fighters are already having three attacks and paladins are adding a flat 1d8 to all of their attacks TWO levels earlier.
17th lvl: Increase Hunter's mark damage to 1d10 and give the Ranger one use of it back if they roll initiative.
20th lvl: The ranger can now cast Hunter's mark at will without expending a spell slot (how this isn't already the capstone is baffling to me). And let them target a second target when they cast a spell a number of times per day equal to their Wisdom modifier.
1st level; Leave as is. It's a perfectly fine feature at this level and frankly at this point Hunter's Mark needs concentration in order to prevent multi-classing shenanigans.
Either 5th, 7th, or 9th level: They get a new feature that allows them to cast Hunter's Mark without concentration. It's still early enough that players will actually get to use it, but late enough that multi-class optimizers won't label it as a "must have". Additionally, the true competition for a ranger's concentration slot doesn't actually start until 2nd and 3rd level spells anyway. I'm leaning towards 5th or 7th level.
13th lvl: Grant the advantage to all attacks to a marked target HERE from the 17th level feature with Hunter's mark.
I might also possibly Increase the hunter's mark damage to 1d8 here as well for better scaling towards 20th level. This is the real part where that feature would actually feel good and it's not as potent as people think. Remember at this point fighters are already having three attacks and paladins are adding a flat 1d8 to all of their attacks TWO levels earlier.
17th lvl: Increase Hunter's mark damage to 1d10 and give the Ranger one use of it back if they roll initiative.
20th lvl: The ranger can now cast Hunter's mark at will without expending a spell slot (how this isn't already the capstone is baffling to me). And let them target a second target when they cast a spell a number of times per day equal to their Wisdom modifier.