In 67 BBY, Lord Tenebrous learned of a cortosis deposit on the planet Bal'demnic, and personally went there to survey it with his apprentice, a treddroid, and an M-2 mining probe droid provided by Subtext Mining. Neither Tenebrous nor Plagueis knew that the droid had been sabotaged. Inside a cave on the side of a steep escarpment on the shore of the Northern Sea, the two Sith Lords landed their craft. The sabotaged M-2 found a gas pocket, and instead of listening to orders of its Sith masters, the droid blew up the gas pocket, resulting in the mine collapsing on the ship. This afforded Darth Plagueis the opportunity to kill his master by letting debris from the explosion collapse on Tenebrous.
In 67 BBY, Lord Tenebrous learned of a cortosis deposit on the planet Bal'demnic, and personally went there to survey it with his apprentice, a treddroid, and an M-2 mining probe droid provided by Subtext Mining. Neither Tenebrous nor Plagueis knew that the droid had been sabotaged. Inside a cave on the side of a steep escarpment on the shore of the Northern Sea, the two Sith Lords landed their craft. The sabotaged M-2 found a gas pocket, and instead of listening to orders of its Sith masters, the droid blew up the gas pocket, resulting in the mine collapsing on the ship. This afforded Darth Plagueis the opportunity to kill his master by letting debris from the explosion collapse on Tenebrous.