Arc of death

The Arc of Death is the third weapon used by the Mage from Hexen. It is a spell that consumes five Green Mana to summon a great bolt of electricity from floor to ceiling, which travels in a straight line away from the player. When the bolt strikes an enemy, it will follow them around inflicting damage for three seconds before it wears off, or until the target dies. This weapon is very effective against the centaurs and slaughtaurs, as they specifically take triple normal damage from this weapon.

Trivia
The Arc of Death is one of two weapons that cannot be spawned in Hexen's ACS, the other being the Firestorm.