Swarm of Bones

Make a 30 ft. by 5 ft. line, a 20ft. cone, or a 10ft. radius attack in a spot you can see within 30 feet of you. When you use this effect, each creature in the area must make a Dexterity saving throw. The DC for the saving throws equals 8 + your Intelligence modifier + your proficiency bonus. A creature takes 1d6 damage on a failed save, and half as much damage on a successful one. The damage increases to 2d6 at 5th level, 3d6 at 11th level, and 4d6 at 17th level.

When you use this trait, roll 1d4; if you roll a 4, some of the bones in the attack glow light blue, and the targeted creature takes half damage if they failed the saving throw, or full damage if they succeeded on it.