Starting at 3rd level, you learn an additional spell when you reach certain levels in this class, as shown in the Monster Slayer Spells. The spell counts as a ranger spell for you, but it doesn’t count against the number of ranger spells you know. You can cast each of these spells once without consuming a spell slot or providing components, regaining spent uses on a long rest.

At 3rd level, you gain the ability to peer at a creature and magically discern how best to hurt it. As a Bonus Action, choose one creature you can see within 60 feet of you to become your quarry. You immediately learn 

• Creature type

• The creature’s armor class

• The creature’s movement types and speeds 

• whether the creature has any damage immunities, resistances, or vulnerabilities and what they are.

• Whether the creature has any condition immunities and what they are

• Any special senses the creature has and their ranges

• The creature’s passive perception

• Any special traits triggered or interrupted by a damage type and what they are

The first time on a turn that you miss your quarry with an attack, you gain an additional 1d6 to the roll, possibly turning the miss into a hit. This benefit lasts until you finish a short or long rest. It ends early if you designate a different creature.

At 7th level, you gain extra resilience against your prey’s assaults on your mind and body. Whenever the target of your Hunter's Sense forces you to make a saving throw and whenever you make an ability check to escape that target’s grapple, add 1d6 to your roll.

At 11th level, you gain the ability to thwart someone else’s magic. When you see a creature casting a spell,  making a spell attack, or teleporting within 60 feet of you, you can use your reaction to try to magically foil it. The creature must succeed on a Wisdom saving throw against your spell save DC, or its spell or teleport fails and is wasted.

You may use this feature a number of times equal to your proficiency bonus, regaining uses on a long rest.

At 15th level, you gain the ability to counterattack when your prey tries to sabotage you. If the target of your Hunter's Sense forces you to make a saving throw, you can use your reaction to make one weapon attack against the quarry. You make this attack immediately before making the saving throw. If your attack hits, your save automatically succeeds, in addition to the attack’s normal effects.