At the end of the daedric quest "Ill met by moonlight", if I obtained both the ring of hircine and the saviour's hide (by killing both the hunters and Sinding), do they both count towards the oblivion walker achievement?

I want to know this because I want to keep Erandur as a follower at the end of the "waking nightmare" quest instead of getting the skull of corruption to get the achievement, so I figured if I got two daedric artifacts in one quest and none in another, then theoretically they should balance out and i should be able to get the achievement nonetheless (provided I did all the other daedric quests properly and got their daedric artifacts).

they both count. just make sure you get the masque instead of the axe.

Thanks. And yeah i already got the masque. IMO, it was waaay better than that crappy axe anyways

I agree. Stoopid axe.

Thought I heard somewhere that the Ring didn't count.

it does. its an exploit though, dont think it was intended that way.

It does, indeed, count, but you're not really supposed to be able to get both it and the Savior's Hide at the same time. What's supposed to happen is that you choose to speak to either the spirit or the stag, and as a result the former does not force-greet you like quest-givers often do; a combination of this and an oddity in the script allows one to avoid the spirit, go outside to speak to the stag for the Ring, then go back in and speak to the spirit for the Hide.

A side benefit of this, which is likely equally unintended, is that you can get the achievement without ever joining the Thieves' Guild; normally you'd need to get the Skeleton Key from Nocturnal to do so, but since the 'glitch' allows you to get an 'extra' Artifact you can get 15 of them without it.

Skeleton Key doesn't count, but that still leaves 15 artifacts that you can acquire (16 if you glitch the Hircine quest as discussed).

You could also save Waking Nightmare for last, save before taking the skull, and then reload the save once the achievement pops.

It doesn't? Then a note for said achievement on the wiki is wrong, as it claims said item is required. Not that that surprises me, given the free-form editing nature of the site, but one would think they would take the time to check the veracity of such statements.