I would take a different approach to it.

A brilliant sharlayan researcher who was studying the crystal tower and time travel had a brush with the Blasphemies and lost someone they were close to. Unable to bear the grief the researcher steals the time travel device and modifies it before jumping into the atiascope and using the unbound aether to power the device and travel to a different time with the intent to change recent history and save their loved one.

Concurrently, some researchers at Alexander get some unusual readings indicating Alexander may be awakening/becoming more active and request the help of the WoL to investigate due to our history with it. Inside, Alexander informs us someone has attempted to alter history at several points in time. Of course, we can't let that happen so we make a deal with Alexander to send us back to those times to prevent those changes.

The researcher was unable to harness sufficient power in the atiascope to make a change in the source so devised a way to capture aether from the source and channel it to the device. The researcher tapped into the periods in history with the highest amounts of ambient aether, the cataclysms at the end of each era, and siphoned that power. Removing that amount of aether would have drastic effects on both the source, the rejoining and the ascian plans which would end up rewriting history.

We could then have an expansion investigating one or two eras each before culminating in finding the researcher in the atiascope and destroying the device.