If I'm not mistaken (and I triple checked), a Ranger has spell slots up to 5th level (2 spell slots). Hail of Thorns is a 1st level spell, and if cast at a higher level, it gets an extra 1d10 per spell slot level above 1st, so a 2nd level spell slot does a total of 2d10 dmg, a 3rd level slot does 3d10 dmg, and so on. This spell has a limit up to 6d10 dmg, so how can I cast it to achieve that 6d10 dmg? I mean, a 5th level spell slot would do 5d10 dmg, so where does the extra 1d10 come from? Am I missing something?
Hail of Thorns
Casting Time: 1 bonus action
Duration: Concentration, up to 1 minute
The next time you hit a creature with a ranged weapon attack before the spell ends, this spell creates a rain of thorns that sprouts from your ranged weapon or ammunition. In addition to the normal effect of the attack, the target of the attack and each creature within 5 feet of it must make a Dexterity saving throw. A creature takes 1d10 piercing damage on a failed save, or half as much damage on a successful one.
At Higher Levels. If you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d10 for each slot level above 1st (to a maximum of 6d10).