"So," says Bella to Rúmil one afternoon, "a few weeks ago I told myself that if in a few weeks I had not come up with an actually good way to bring up a thing I would just mention it anyway on the grounds that if it came up somehow later and I had not done so that would be weird."
"Yeah. 'daeva are only contained by the fact they're either incurious enough not to have followed up on the multiple clues they have at this point or altruistic enough not to have made it apparent they can' is a disastrously unstable situation. There's got to be either a wizardry or a spellbinding or an eclipsed or at worst a wished-on way to contain them. Develop it. Then recruit harder, there are a lot of security measures you could take if you weren't constrained by only having one and a half demons. Have a couple dozen; have people checking hourly for anyone outside their native dimension; know about it before it even happens every time; develop a procedure that also catches people who aren't conjurable. Don't trust the Valar to do anything more complicated than 'speak in complete sentences'; as soon as you land on a world and before its Sauron and Melkor learn interdimensional transit is a thing that even in principle exists, summon them out to an uninhabited planet and hole it."
"Most Ardas are found after they find that interdimensional transit is a thing that exists."
"That's why you have to kill them as fast as you possibly can."
"Sibyl should be able to tell you, but - yes. A million people dead is less of a disaster than a loose Enemy, especially now that you can bring them back. He's in Warp, now, imagine if Warp hadn't been the Telperion neighbor with the most people and we hadn't been able to find him at all and he was now in some other dimension with several trillion people in it, with wizardry and an apparent agenda of getting them all to destroy each other as entertainingly as possible."
"Can she see, like, the future life of some random citizen on his planet?"
"So if they vanish from her view when we form Sauron-related plans, he has a deadman's switch."
"Fair enough, but we're not actually sure how he's knocking her out. He can't have been expecting her in particular and Maiar don't do it by default, so he has some kind of wizardry defense which could be misleading in other ways."
"Yes, it could. Can anyone do spell cancellation? What's been tried -"
"Counterspells are possible in principle but Boots doesn't want to count on it especially versus a Maia wizard; antimagic fields likewise. She's not even positive her anti-teleport spell will work; Valar can forbid wizardry on their turf, specifically or in general, and didn't need a lot of prep time to do it so a Sauron could replicate the trick."
"And he might not have teleported with wizardry - or, even if he did, he might know another way to do it, Shadow's did. Though Ithil's didn't and they were highly motivated, so that at least seems to require some prep time. What about wished on or spellbinding anti-wizardry, what about the rings of power -"
"Some magic rocks have some potentially relevant powers but Sibyl can't tell how they'll interact and Gem can't reset time outside her neighborhood. Spellbinders are working on it but keep hitting blind alleys since a spell can click just fine as long as it works in the context of Hex whether or not it actually has the desired effect on other magic systems. Rings of power I don't actually know..." What does the network have to say about rings of power these days.
Reconstruction of Sauron-proof ones is proceeding apace but that's Elf pace, it'll be at least a couple years. Elrond and Galadriel and Gandalf have the existing Sauron-proof ones though Celebrimbor thinks he can do better next go round. When done they should effectively make the bearer a Vala, and therefore probably work for wizardry cancellation because Valar can do that but it kind of depends how much of the 'acting within a specific area' and 'everything very slow' constraints are actually part of the magic compared to being part of Vala personality.
...okay, do the existing bearers maybe want to loan them out or make a housecall.
I can drop by and ask. None of them are indestructible - well, actually, I think Gandalf's a Maia?
That would probably, you know, help, I was not super looking forward to having to approach a Sauron to teleport him against his will.