Phase III Dark Troopers were the most heavily armed and armored class of Dark Trooper.
The first appearance of a Phase III was in Star Wars: Dark Forces, where it served as the game's final boss. They later appeared in Star Wars Galaxies: Trials of Obi-Wan and Star Wars: Empire at War: Forces of Corruption as more common Imperial units.
Empire at War: Forces of Corruption[]
A Phase III Dark Trooper in Forces of Corruption
The Forces of Corruption variant of the Phase III Dark Troopers function more as bipedal tanks than as heavy infantry. They have blaster cannons grafted onto their arms that can shred light tanks and infantry. They can also be deployed in siege mode to fire proton torpedoes that can decimate aircraft and heavily-armored tanks with ease. Their slow movement is their only weakness, but that can be compensated for by using the jetpack function to have them fly across the battlefield. However, the jetpack needs recharging after use, so use of the jetpack should be wisely timed and reserved for emergencies. Having a group of Phase 3 Dark Troopers is effective in shredding any sort of opposition, but they are costly to make and take up one whole supply unit per trooper. And in Galactic Conquest, only the planet that has the Arc Hammer orbiting it can produce Dark Troopers. So mass-producing them will take time, but it will be worth it to overwhelm the enemy with such high-end units that can shred infantry, tanks, and aircraft with ease.
Dark Forces[]
The Phase III Dark Trooper in Dark Forces is equipped with the same jetpack and Assault Cannon as the Phase II, but has an additional weapon that fires yellow energy spheres (five at a time). Allegedly, these originally homed in on the player; but due to a bug in the game's code, on all modern systems (Mac and PC) they just float in place, allowing the player to shoot and detonate them to do added damage to the Dark Trooper.
Unlike the Phase II, the Phase III can walk in addition to flying.
Since the Phase III appears at the end of the game anyway, it doesn't drop any items when it dies.
Due to the limited number of enemy types in Dark Forces, Phase IIIs have appeared in many fan levels for the game; however, it's generally considered poor style to use them in a level.