The Hellex Plasma Mortar is a plasma-based artillery system used by the Thanatar-class Siege Automata of the Legio Cybernetica during the Great Crusade and Horus Heresy eras of the late 30th and early 31st Millennia. The Plasma Mortar fires high-density charges of burning plasma timed to detonate over their targets.
These airbursts create rolling waves of incinerating energy which engulf the surrounding area and are particularly useful in siege warfare, since they can be used to bypass static defences and strike at the soft heart of fortified positions.
Starship Plasma Mortars
Larger pattern Plasma Mortars are also mounted in powerful batteries on Ramilies-class Starforts as space defence weapons. They form part of each starfort's overwhelming defences and are extremely powerful weapons at long-range.
- The Horus Heresy Book Three: Extermination (Forge World Series) by Alan Bligh, pg. 227