Indeed, but obviously I'm suggesting more effects, more like a menu you choose from at lower levels to customize your hunter's mark. An evolving hunter's mark that can have one aspect changed on a long rest creates a strong central identity and IMO does the job better than the spell does. Customizing your Hunter's Mark before going into a dungeon or big forest or traveling across the sea to have effects like:
- The target is exudes a soft light in darkness, making it visible.
- The target has disadvantage on Strength or Dexterity checks.
- The target can be charmed instead of suffering the extra damage.
- The target can be feared instead of suffering the extra damage.
- If you hit the target twice on one turn, you can sacrifice the HM damage to daze the creature.
- Your speed increases by +10 when moving towards the target.
- You have advantage on saving throws against magical effects from your target.
- Your attacks crit on a 19-20 against the target.
- You can hijack the target's senses once while it is marked.
- You can read the target's surface thoughts for as long as it is marked.
- You reduce the target's movement speed by -10 instead of dealing the extra damage.
- Changing the damage type of hunter's mark.
- Allowing the party to trigger hunter's mark damage + rider effects.
- Give the target disadvantage on saving throws against your spells.
- Make the target leave a bloodtrail wherever it goes.
- Afflict the target with a poison that has a unique effect.
- Remove the target's resistances until the end of its next turn instead of suffering the extra damage from an attack.
- Making a target unable to heal while marked.
- Make the target lose one proficiency while marked.
- Give the Hunter's Mark a creature type-theme, which gives it a unique rider effect, like producing Dragon Breath on a target or scrambling their thoughts ala aberrations.
By putting these basic effects into menus for Hunter's Mark, you can create more interesting Ranger Spells that fill more niches, similar to spells like Guardian of Nature or Cordon of Arrows. You could also cut the fat from the Ranger spell list as well, leaving it more thematic overall and transferring some of that mechanical weight to the Hunter's Mark customization.