Arbalists are fighters who prefer the use of crossbows over all other weapons. 

Elemental Arrows

starting at level 3, you learned how to infuse your arrows with the power of the elements. During a short or long rest, you can infuse your arrows to deal with cold, fire, or lightning damage. you can infuse up to your proficiency number arrows, you can mix and match the elements.

the infused arrow losses its power after a day or after a short rest

at level 5 the infused arrow does 1d4 extra damage, 1d6 at level 7, 2d4 at level 10, 1d10 at level 15, and 2d6 at level 18. 

Arrows Master

at level 7, the quickness of your hand allows you to ignore the loading property of a weapon.

Arrows Barrage

at level 7, your control over the crossbow allows you to instead of rolling to attack, fire a barrage (10) of arrows into the sky dealing massive aoe damage. 

You can force all creatures within a 90ft, 10ft radius to make a dex save.

On a failed save, the target takes the usual damage, on success, targets take half. 

this feature does not work with elemental arrows. 

you can use this feature once, recharge after long rest.

 

Proper Form

at level 10, you mastered your crossbow to attack with pinpoint precision. when attacking, you can add double the prof bonus to your attack roll instead. 

you can use this feature once per long rest.

you gained the sharpshooter feat if not already have it. 

Armor Piercer

at level 10, you honed your arrows to be able to pierce through armor. if the target has medium or heavy armor, you can choose to ignore the benefit of said armor when attacking. 

when activated, the target also takes 1d6 extra damage.

you can use this feature once per long rest.

Front Mortar

starting at level 15, you learned to take advantage of enemies at a close range. when the target is within 10ft of you, you can add half your fighter level (rounded down) to the damage dealt. 

Being within 5 feet of a hostile creature doesn’t impose disadvantage on your ranged attack rolls.

Riot Shot

at level 18, the deadly shot of your arrow is feared by all. you can crit on command. when criting using this feature, you roll one additional weapon die when calculating damage. it deals fire, cold, and lightning damage, ignoring resistance and immunity.  

you can use this once per 1d4 days.