The Ancient Threat

The 'Ancient Threat' is a manifestation of the convergence of dark side energies caused by the reawakening of the spirits of Naga Sadow, Tulak Hord, Marka Ragnos and Exar Kun:


For those wondering, it looks like this:



The 'Ancient Threat' is literally too powerful a source of energy for the 'galaxy's greatest heroes' to damage:



Unless their Force essences are touched by the four spirits:



And they must collect their individual talismans to even find it in the Force:



Once they do actually face it, it's easily too powerful for any minor group or one of the protagonists and literally requires a full group of 24 of the galaxy's champions to destroy it like a Nightmare Op. This thing is the Yavin IV world boss.

To put it simply:

1.The mere presence of the four spirits in one place caused a convergence in the dark side of the Force that manifested into a malevolent source of dark side energy.

2.The 'Galaxy's Greatest Champions' as of Shadow of Revan, the group that always face these things; I.E Dread Masters operations, is required to destroy it and even then they had to use specific items to do so.

This is an insane depiction of the power of these spirits, given that this manifestation of dark side energy was a mere side-effect of them being awoken on Yavin IV at the same time.

Well, I imagine it being caused by three bona fide Ancients and a 350 year old spirit is probably where it gets the name.

I mean Marka Ragnos also lost to Jaden Korr, so.

Marka Ragnos freshly resurrected in a body that was literally disintegrating from the power of his spirit. In other words Ragnos >> Spirit of Ragnos >>> The limits of power Tavion could handle > Jaden Korr.

The return of the spirits of Kun and Ragnos also caused the Force to 'seethe' with malice.