It was an ancient machine referred to in several texts alongside apocrypha depicting the power of Darth Nihilus. The Siphon was exactly what was depicted in the ancient stories—a machine of Rakatan design capable of stealing the Force energy from one being…. and steal it for another.
Similar to machines and artifacts found in the depths of the prison on Belsavis, Siphon was controlled by a series of relics referred to as The Keys. One key, lightweight and bronze in color, had the power to collect Force energy, and contain it. A second, matte black and seemingly made of a Force-resistant alloy, also consumed Force energy, but used the energy to power the machine.
A third key was rumored to have the power to transfer power from one willing Force user to another willing Force user—but the transfer of such vast amounts of energy tended to destroy the body of the recipient, just as the loss of so much power tended to cause fugue or even spontaneous coma and death in beings who sacrificed more of themselves than they could afford to lose.
There were three other keys whose powers remained unknown, and were never uncovered—but it was known they were useless without the others. They were last known to have been stored together, and might even have been destroyed incidentally near the end of the Great Hyperspace War.
Further information was known to have been researched by a Fallen Jedi, and retained in a datacron outlining force suppression techniques used by the Jedi Council. The loss of the force suppression knowledge was a serious blow to the Jedi, and without the machine, the remaining information about Siphon was useless. Eventually, the datacron was stored in a box lined in materials known to resist Force energy.
Very few of these “force null” boxes were known to exist, which ultimately made the technology easier to find, instead of harder.
According to instruction, the keys could be used to influence an sentient device known as the Mother Machine, capable or reorganizing biomatter at the subatomic level. According to Mother Machine’s databanks, she may have influenced the creation of a thousand life forms, including twi’lek and a dozen other intelligent races as servitors for the Rakata. It was believed she was being used to genetically enhance a Force-sensitive species, giving or taking away force ability from any species it has the ability to remake.
The keys could also be used to control Mother Machine. The sheer scope of danger this possibility represented was enough to cause the council of the Teras Kasi to locate the keys, and destroy Siphon.
This had the unintended effect of freeing Mother Machine, who chose to set out across the galaxy in search of previous versions of her own program—in essence, predecessors. While there have been rumors, she has not been definitively heard from since.