Phase III Dark Trooper
The most deadly soldier the Empire has ever come up with, the Phase III is the final stage in Dark Trooper construction. Brain child of General Mohc, the Phase III has the same weapons as the Phase II plus some energy orbs that seek you out until destroyed. The Phase III appears slightly slower than the Phase II, but the extra armor and weaponry make up for the loss in speed.
Suggested Method of Attack - You'll only face one Phase III in Dark Forces, but the add-on levels are another matter. For the one in Dark Forces you can lay mines around the column at the beginning. But once it gets in the open heavy firepower is your best friend. Start with the Assault Cannon launching missiles and plasma like crazy. Try to take out energy orbs when you can since the resulting explosions will damage the Phase III. Avoid the plasma in the same way as for a Phase II and just keep shooting. If you can find a concealed area with a low enough entry to prevent the DT from firing then you can pick it off at your leisure. Otherwise the battle comes down to who can score the most damage in the shortest time. Nothing fancy, just lay into him and keep moving.