Orthus is a set of dual-wieldedKriss submachine guns with a red, silver and black finish.
The weapon has many huge improvements over the Dual Skorpions such as a lot tighter bullet spread, lower recoil, larger ammo capacity, faster reload, more damage and greater portability. Dual Skorpions are completely inferior to the Orthus.
Currently, it is available from the Supply Crate MYST-Quebec and the Soldier's Fortune. Just like the Legion, the Orthus' duration can only be renewed by the Demonic Renewal Kit due to balancing reasons.
This is the third weapon that does not belong to a mercenary, the others being the Azazel and the Legion.
This is the second known set of dual-wielded weapons. The first was the Dual Skorpions.
This is the first weapon to be a dual-wielded one.
This weapon was originally discovered, along with other weapons, inside the game's .rez files.
Before the recent patches, there was a glitch: if a player died whilst holding the gun, the weapon would drop but would be inconspicuous - only a red speck would be visible.