Dungeons & Dragons Lore Wiki

A blue bolt is a stroke of lightning of apparently divine origin, used to punish the unworthy.

The Advanced Dungeons & Dragons 1st edition Dungeon Masters Guide recommends the use of blue bolts as a metagame mechanic to punish disruptive players:[1]

"Strong steps short of expulsion can be an extra random monster die, obviously rolled, the attack of an ethereal mummy (which always strikes by surprise, naturally), points of damage from "blue bolts from the heavens" striking the offender's head, or the permanent loss of a point of charisma (appropriately) from the character belonging to the offender."