In Avernus Cathedral, Kain met and defeated the Lady Azimuth, guardian of dimension. Along with her Third Eye Pendant, Kain found Azimuth had a Time Streaming Device, which she had explicitly been planning to use to summon creatures from other ages as well as other dimensions.
Kain carried the device with him with caution, advised by Ariel that it was his salvation and would "deliver [him] in time". When Kain was caught up in the Battle of the Last Stand and the Army of Hope was destroyed Kain was left hopelessly outnumbered by the Legions of the Nemesis ; The Device activated, saving Kain from a certain death.
Kain discovered that he had been transported 50 years into Nosgoth's past and had been presented with an opportunity to rid Nosgoth of the tyrant the Nemesis. Unfortunately the Time Streaming Device had shattered, leaving Kain stranded in the past.
When Kain travelled to the Land of the Nemesis, he found Moebius supplying William ; the boy-king who would turn tyrant. Kain confronted William and found he was also armed with the Soul Reaver blade, upon killing William, Kain luckily found that he was in possession of another time streaming device, which enabled him to be transported back to his native time period.
Shortly afterward Kain was able to discover the changes he had wrought and found that his actions had allowed Moebius to ignite another vampire hunting crusade that of Moebius's mercenary army . Furthermore, Moebius had been manipulating his journey for a long time and it is likely that Moebius was responsible for both the Time Streaming Devices Kain found.
The Time Streaming Device looms large in further adventures - the Time Streaming Device found by Kain on Azimuth had already been used by Azimuth to retrieve the (d)evolved Turel from the far future to act as an impressive mouthpiece for the Hash'ak'gik Cult.
Unlike the much larger the Chronoplast seen in Soul Reaver or the Time Streaming Chamber seen in Soul Reaver 2, the Device cannot change locations and seems to be much more difficult to set. It may also be that they are one-use, or one direction only as Kain's shatters once it is used. Though this is presumably contradicted by Azimuth's use of it. It could be that the Devices are just incredibly fragile.
There is debate amongst fans as to how conscious Kain's choice to use the Time Streaming Device at the Battle of the Last Stand was. He could presumably have escaped using Bat Form or any number of his spells. Given that the player never selects them from the menu, it may be that they were previously set (likely by Moebius) and automatically activated. William the Just holding the Time Streaming Device is presumably further evidence of Moebius' interference in Kain's journey. The Time Streaming Device is seen in no other games, although events in Defiance seem to depend upon its use.