Storm Shooter Feat

Prerequisite: 4th Level

• Ability Score Increase. Increase your Strength, Dexterity or Constitution by 1, to a maximum of 20.
• Raining Death. If you kill a creature within a single ranged weapon attack (reducing it from maximum hit points to 0 hit points) using the Attack action on your turn, you can make one additional ranged weapon attack as a bonus action that turn.
• Gain the Arrow Storm special attack (below).

Arrow Storm - Activty Ability (Attack)

• When you take the Attack action on your turn, you can replace one of your attacks by firing inumerablepieces of ammunition into the sky which rain down around a point within 60 feet of you. All creatures within 10 feet of the point must make a Dexterity saving throw. On failure, they take 2d6 + your Dexterity modifier damage, or half as much on success. The number of d6 damage dice increases by one when your proficieny bonus increases (with the total number of d6 equaling your proficieny bonus).A number of pieces of ammunition are consumed equal to the number of targets that make the save against the ability times two.

Once you use this feature, you cannot it again until you complete a short or long rest.
Source: KCLL, page 185

Active Martial Feat Save DC:

• Any time an active martial feat requires a saving throw, the DC is 8 + your Strength or Dexterity modifier (your choice) + your proficiency bonus.