Based off of research into antimatter weaponry and named after the ancestor of all explosive siege weaponry, the TL-25 "Mortar" is a battleship-scale artillery weapon that is commonly found on battleships and dreadnoughts throughout Sirius. The weapon contains a cryogenics package that condenses and supercools hydrogen around a fullerened antimatter payload into a supercooled "slug" of antimatter-doped hydrogen ice. The projectile is then sent down a barrel containing a number of graviton-generating toroids, which, at the cost of a significant amount of power, attract and repel it in sequence like a gauss gun, imparting a minimum of heat on the outer layers of hydrogen ice while accelerating it to an effective velocity.

The unquestionable superiority of the Mortar in capital warfare for long-range engagements compared to the relatively close-quarters plasma projectors used in Cerberus-type turrets, combined with the efficiency of a primarily energy-based weapon in a battle of attrition in contrast to conventional torpedoes, resulted in variants of the weapon being developed for cruisers and later battlecruisers, as well as a higher-input, higher-output version commonly known as the "Heavy Mortar". Regardless of the variant, the success of the Mortar ensured that the family of weapons would be seen on just about every warship in Sirius for centuries to come.