Self defense should permit us to cause the minimum harm to an assailant necessary to if possible remove the barriers to flight or dematerialization and if impossible prevent being harmed, and not more than that. 'cause' is an acceptable revision. Two years for vat blood?

Do they even actually need sapients' blood? Even if they did, somebody managed prizewinning sashimi-grade tuna in a vat in a year and a half when the prize was just thirty million dollars and I think you want Valinor gone more than that and can beat a garageful of two humans and an angel at biology. What do the Elves think of the self defense clause? Do oaths allow convolutions like "if and only if the entirety of the spirit of this oath is intact"?

Six months for blood, then? The Elves are happy to allow the self-defense clause; if they die murdering the Enemy Cam can bring them back anyway and they were planning to wait until they had options sophisticated enough he wouldn't see it coming. Convolutions are super dangerous and self-referential bits in oaths are super dangerous and they probably won't get much of anywhere with that; they could do 'if attacking me is not warranted under fundamental rights law to prevent future instances of crimes committed after I swore this oath'?

With some tweaks to the phrasing, sure.

Brick.

Six months it is. We can do that with donors. It will take a few days to cause everyone Melkor can cause to take this oath to take the oath. You can check continually or we will notify you when we're done.

I would appreciate a notification.

Cue Cam spending several days aggressively trying to relax, doing a lot of furious writing in his computer, and playing unhappy violin.

Macalaure sings songs that are only obviously distressed if you know what to listen for. Fëanáro and Curufinwe work nonstop.

And a few days later, torpedos give the bunker a light tap. 

That is not a particularly polite notification.

Cam summons up what he needs to summon up.

Cam has three dozen oaths exactly as specified. Melkor's and Thauron's are among them.

Well.

Okay then.

Wish him luck. Or skill. Whatever.

"...I am not completely sure that when he realizes you've gone off in a lightleaper Findekano won't decide to let something slip around Huan," Maitimo says. 

"...worrying."

"Yes. Do you have any ideas."

"I don't have any good ideas but it may be past time to stop pretending I inevitably hold out for those."

"Likewise, except I got an earlier start on the coming to grips with that."

"Options basically all boil down to 'don't let him find out I left' and 'don't let him tell when he does'. First group's gentler. Think it's got a prayer?"

"Given that you and my family have obsessively been working together for the last while and he knows what to look out for and you are not frequently gone for a week, I don't think so."

"Well damn. I do not know that I can corner him in a room to osanwë-proof, beautify, and leave him in for the duration. Not that good an actor."

"I am. Or - while I was gone Medical sorted how to safely knock us out for a while, didn't they? That was one of his projects, too...."

Cam scans the latest of the medical results to refresh his memory of the details on that.

Not yet. Not safely. 

"Not as such no."

"Well. I can do it, if you want to take me back down there."

So Cam takes him back down.

And a couple people definitely turn and stare in something that looks like recognition but it's too late for that to matter.

Hey. I just got back from pretending to be dead landside, think I've mostly caught up on things.

Oh, so you haven't been in on the negotiations with the Enemy about how to destroy Valinor?

No but it's what I wanted to talk with you about, it's the same thing I said at Alqualonde, we have to give my father alternatives, and you thought of how to bring back the dead when he didn't, maybe you can do this when he didn't. 

I've been trying.

I'm still pretending to be dead can you please come meet me at the airlocks so I don't have to test this disguise much? Don't think it'll hold up.

I'm stunned it did at all. Were you not just ordering people left and right to pretend they didn't see you?

Nah. People weren't looking closely.

And he comes to meet them.