You have a limited well of physical and mental stamina that you can draw on. As a Bonus Action, you can use it to regain Hit Points equal to 1d10 plus your Fighter level.
You can use this feature three times. You regain one expended use when you finish a Short Rest, and you regain all expended uses when you finish a Long Rest.
Tactical Mind: You have a mind for tactics on and off the battlefield. When you fail an ability check, you can expend a use of your Second Wind to push yourself toward success. Rather than regaining Hit Points, you roll 1d10 and add the number rolled to the ability check, potentially turning it into a success. If the check still fails, this use of Second Wind isn't expended.
You invoke spirits of nature to magically hide yourself. As a Bonus Action, you can give yourself the Invisible condition until the end of your next turn.
You can use this feature a number of times equal to your Wisdom modifier (3 times), and you regain all expended uses when you finish a Long Rest.
You magically mark one creature you can see within range as your quarry. Until the spell ends, you deal an extra 1d6 Force damage to the target whenever you hit it with an attack roll. You also have Advantage on any Wisdom (Perception or Survival) check you make to find it.
If the target drops to 0 Hit Points before this spell ends, you can take a Bonus Action to move the mark to a new creature you can see within range.
Using a Higher-Level Spell Slot. Your Concentration can last longer with a spell slot of level 3 or 4 (up to 8 hours) or 5+ (up to 24 hours).
You always have the Hunter’s Mark spell prepared. You can cast it 4 times without expending a spell slot, and you regain all expended uses of this ability when you finish a Long Rest. When you cast it this way, it does not require concentration.
Briefly surrounded by silvery mist, you teleport up to 30 feet to an unoccupied space you can see.
You always have Misty Step prepared and can cast it once without using a spell slot.