The Tantalus is built by the Arm Level 3 Construction Vehicle. Once constructed, it offers the player three operating modes on the left-hand side build menu to choose from: Commander Hack, Radar Jamming, and Radar Targeting. Only one of these options can be activated at a single time, and each one uses a differing amount of energy. To activate an option, the player has to left click the option on the left-hand build menu.
The Commander Hack option allows the player to locate the enemy commander by producing a field of line-of-sight around him, revealing the commander and nearby units. If there are more than one enemy players, the commander hack will randomly rotate between all enemy commanders, effectively revealing the location of all of them. The commander hack can be countered, however, by building decoy commanders, which the commander hack will also reveal, confusing the player using the commander hack as to which one is the real commander.
Fitting with the Arm's stealth doctrine, The Radar Jamming option allows the Arm player to jam the entirety of most decent-sized maps, allowing friendly ground troops to move about undetected and hiding friendly bases, rendering enemy radar useless. Note, however, that this option does not provide sonar jamming.
The final option available to the Tantalus is the Radar Targeting option. This option replaces the original Radar Targeting Device from OTA. By activating this option, the player enables his units to fire at all hostile units that appears on the Radar map, much like the functionality of the radar targeting device.
When the player wishes to turn off any of the options, all he has to do is right click the option currently active. To switch to another option, the player must first deactivate the option currently active.