Bolt deals by default 30,000 damage to a unit, which is then reduced by the targeted unit's hack-, pierce-, and crush armor, according to the following formula:
Damage dealt = 30,000 - 10,000*(H+P+C), where H, P, and C are the unit's hack-, pierce-, and crush armor, respectively (in percent). Titans are normally (outside of custom scenarios) the only targets capable of surviving a Bolt; a Titan survives taking 1,250 damage, which is only half of what it is supposed to take when using the formula above.
Though an Archaic Age god power, Bolt is often more useful in later Ages. It is best used on powerful units, which will make an enemy army more vulnerable. It can come in useful early in the game by killing enemy scouts or by taking out Norse infantry which will hinder their ability to build and their ability to advance to the Classical Age if they have not constructed a Temple yet. Alternatively, players can target units limited in number, such as Greek heroes or the Pharaoh. Bolt can also be used to deal with powerful enemy units created by other god powers, particularly Son of Osiris and Nidhogg (except in the Extended Edition, where they only receive 1% and 2% damage respectively). Players can use Bolt against an enemy Titan, but there will still be the need for considerable follow-up attacks to kill it.