Here’s the full list:

Billy Gibbons (ZZ Top), Stella Mozgawa (Warpaint), Jake Shears (Scissor Sisters), Mike Kerr (Royal Blood), Carla Azar (Autolux, Jack White), Les Claypool (Primus), Matt Sweeney, Matt Berry (What We Do in the Shadows, Toast of London), Libby Grace (almost certainly a pseudonym) and Töôrnst Hülpft (almost certainly Dave Grohl but could be Claypool, Sean Lennon, Richard Ramirez, Clark Gable, Lux Interior, The Muffin Man or even Trent Reznor).

And what of the songs?

The opener, “Move Together”, is a beautiful take on Tom WaitsMule Variations sound – from the hushed, creaking vocal delivery from Billy Gibbons (who you could easily mistake for Josh Homme himself), to the delicate musical accompaniment, which is only sporadically punctured by blasts of noise. Then there’s “Noses in Roses, Forever”, which is the closest thing to classic Queens Of The Stone Age on the set – which makes it the best thing here. Robotic, lockstep rhythms and rolling riffs that sound like electricity passing through rusted wires. The guitars are undeniably gorgeous.

Instrumental slice “Far East for the Trees” is Led Zeppelin folk in space, and it grows gradually stranger with each pass of the riff. Then ‘Libby Grace’ takes lead vocals for the rather subdued, melancholic cowboy strut of “If You Run”. This is intriguing, not least for the fact that ‘Libby Grace’ doesn’t seem to exist – and is almost certainly somebody we know. Suggestions have been made that it’s Brody Dalle, but who knows? Answers on a postcard.

“Crucifire” finds Mike Kerr, from Royal Blood, taking lead vocals – and it’s probably the best thing he’s ever sang on. Considering that his day job is the leader of Diet Queens of the Stone Age, he does a bang-average job. It’d have been a great bonus track on Era Vulgaris.

“Chic Tweetz” is anything but average. If you can imagine a lost ABBA tune, reimagined by Ariel Pink, then refashioned for early morning kids TV, you’re close – except for the fact that the lyrics are gross. Is it Dave Grohl or Trent Reznor on vocals? Probably.

The collection then closes with a pair of downbeat, navel-gazing plodders. The first, “Something You Can’t See”, is led absolutely nowhere by Jake Shears. The second, “Easier Said Than Done” is only the third song here worth saving after the first two. It’s got that new Josh Homme “Vampyre of Time and Memory” elegiac quality.

In short, it’s a bit of a misfire. But the biggest shame is that Josh Homme is (was?) on the hottest streak of his career. The second biggest shame is that the last Desert Sessions set is the best of the bunch, with all those glorious PJ Harvey vocals and all those fully-written songs.

Vols. 11 & 12 give few answers but leave us with many questions, such as: Where is Iggy Pop? Where is Alex Turner? Where are the rest of Warpaint? Where are all the fucking songs? Who’s even gonna listen to this shit? When can we have a new QOTSA album?