The ethereal sub-commander is an enemy in The Lost Frontier. Holding an unspecified rank of "sub-commander" in the Aeropan military, they operated as the superiors to Aeropan commandos, gladiators, and dark armadillos during several operations.
Every dark warrior is a former Aeropan civilian who underwent similar treatment to that of Jak when he was imprisoned in Haven City via the Dark Warrior Program. This time, however, they were successfully mutated into soldiers capable of being mass-produced.
One was first encountered near the end of the mission "Search the barracks for seeker piece", in a training center inside the old Aeropan barracks. It was only activated once Jak approached, at which point it was elevated from a chamber and appeared to wake from a comatose state.
Three more were encountered during the Aeropan assault on Far Drop in the mission "Fight off the Aeropan shock troops". The first two operated a lightning device, which produced a force field that would act as the range for a shock device. Upon entry or attempt thereof, the device would strike the target with lightning. The first one was situated in front of Barter's tavern, the second one near the crane at the loading docks, and the third one on the top of a docked Aeropan dropship.
A final sub-commander was encountered in Aeropa's weapons control room during the mission "Disable weapons control system". After Jak entered the room, the sub-commander joined from a doorway on the opposite side of the room, suggesting it was guarding the usual way of entry instead of Jak's alternative route, opened up by a friendly bomb strike.
The ethereal sub-commander is a heavily mutated human, like other dark warriors. However, its waist, arms, neck, and legs have been replaced with an electricity-induced cloud-like matter, which appears to bind its body together. Otherwise, its entire body is concealed by armor, somewhat similar in appearance to that of the commando's, but more heavily fortified.
The sub-commander is a fairly simple enemy to fight. Its best weapon is its ability to resurrect fallen commandos, as its other attacks can easily be circumvented by bombarding it with gunfire and persistent eco amplifier attacks (note that it does not appear to resurrect the gladiators).
Early on its ability to teleport to other areas can be somewhat of a nuisance, though eventually you can learn to counteract it with long-range, high-octane mods like the Lobber or Vulcan Fury. The Vulcan Fury is also especially useful to induce stunlock on the sub-commander, though any attacks used in quick succession are able to accomplish this as well. The stunlock can only be broken by the sub-commander with its teleportation.
Its main attack is a ground-pound move, which will create a harmful dark eco shockwave along the ground. Its second attack involves a charged blast of four dark eco bolts, which due to its slow speed is easy to dodge, especially at long-range.