More mages, now, all of them able to summon Daedra to help (though Tolfdir is the only one who can maintain more than one up at the same time), so the battle is not one-sided even though there are over a score walking dead trying to kill them all.

Burn, burn, burn.

The main draugr, though, the one that was on the throne, seems completely immune to any damage, and not even Tolfdir can scratch it. "The artefact is feeding energy into it! Cover me while I try to break the connection."

That makes the battle more one-sided, when one of their foes—the most powerful of them—is categorically indestructible. It also seems capable of wielding thu'um, shouting imprecations in the dragon tongue at them which throw them all clean off their feet and directly at walls.

They soon adopt a formation. Erandur serves as their healer and backline support, Onmund and J'zargo are their heavy hitters for the draugar other than the indestructible one, and Ruby and Brelyna both try to distract the indestructible one and put obstacles on its path so the others can continue to do their own jobs.

It doesn't work perfectly, and there are enough other draugar that they keep overwhelming Onmund and J'zargo, but at least the summoned Daedra can serve as tanks and distractors, themselves, throwing themselves into danger heedless of any damage—their bodies are just magical constructs, after all, and if they're destroyed all that'll happen is they'll be returned to their respective realms in Oblivion.

They mostly need to buy time, though, especially once the only draugr left is boss draugr. At that point they can mostly keep it occupied enough that it doesn't hurt them all too much, though the thu'um are a big advantage, what with how they cost no magicka at all and can't be straightforwardly interrupted.

"I have it! Focus fire!" Tolfdir calls, and as soon as the connection between that artefact and the draugr breaks—

...well, the draugr is actually still very damn hard to kill even without being indestructible. It was a powerful mage in life, that much is clear, and once it becomes clear to it that it can no longer just casually barrel through them with unrelenting force it decides to summon Daedra of its own to up the pressure. It has four of them up at the same time, which not even Tolfdir can do, and it cycles through barriers that completely nullify some types of attacks one by one.

Still, while it must have been fearsome in life, its power is much diminished in (un)death, and six mages are enough to eventually, painstakingly, with a lot of effort, kill it.

When it notices it's about to die, though, it bundles up all the rest of its magic and life force into one final explosion, powerful enough it could have killed all of them had it reached them.

But it did not, in fact, reach them; Erandur and Tolfdir both react quickly enough to contain most of it, and all that happens is that all six of them are covered in third-degree burns and all of their Daedra are dispelled.

Thankfully all of them have healing spells and enough presence of mind to start healing themselves before the agony overwhelms their senses.

It's still nonzero agony, though.

"Now what is this fascinating artefact..." wonders Tolfdir aloud, turning his attention away from them and towards the shielded sphere.

After verifying that everyone is alright Ruby gingerly steps over to the corpse of the draugr. He was, after all, tasked with finding enchanted items.

There are two very visibly magical artefacts on it: one is an amulet around its neck, and the other is a... piece of paper? That seems to be attached to its forehead.

It had not been attached to its forehead before.

Mysterious. What does it say?

Be bound here, Jyrik Gauldurson, murderer and betrayer
condemned by your crimes against realm and lord.

May your name and deeds be forgotten forever
and the charm which you bear be sealed by our ward.

If they wanted his name to be forgotten why did they go and write it on the paper? ...maybe it was necessary for whatever ritual was meant to be sealing this guy here.

"Does the name 'Jyrik Gauldurson' ring any bells for anyone?" Ruby asks, straightening back up and frowning at the seal.

None of them seem to know it, not even the one Nord who was most likely to know of any legends about him, given the similarly Nord name "Gauldurson".

"Seems like the dude was meant to be sealed here and then forgotten," Ruby explains, offering the seal to the others to examine.

"...why did they seal him here rather than kill him?"

"'Tis likely he was too powerful at the time to be killed. If he has been here for thousands of years, his power would have greatly waned since, and this is why we could do it ourselves."

"This makes no sense, though. I thought no one had survived the Night of Tears? I mean, other than those three people who then brought an army and killed all Falmer. What is this person doing here?"

"Khajiit suspects that he is a later addition to these ruins."