Sweeping and Penetrating Attacks

When a melee attack reduces a creature to 0 hit points, any excess damage from that attack might carry over to another creature nearby. The attacker targets another creature within reach and, if the original attack roll can hit it, applies any remaining damage to it. If that creature was undamaged and is likewise reduced to 0 hit points, repeat this process, carrying over the remaining damage until there are no valid targets, or until the damage carried over fails to reduce an undamaged creature to 0 hit points.
Similarly if non-spell ranged attack reduces a creature to 0 hit points, any excess damage from that attack might carry over to another creature behind it. If another creature is in the ranged attacks normal range limit and is standing in a direct line behind the initially hit creature, and the original attack roll can hit it, the remaining damage is applied to it. Just like with melee attacks, this process can repeat as long as there is damage remaining and valid targets.