Kind of embarrasing question...

[UninspiredName]

Turn...File?

At any rate, I'm trying it with a Vampire Queen (What? I like summoning) pretender and the Gray Ones, (I think. The one-eyed crowd where the closest thing to a ranged attacker is a giant that throws boulders) five levels in blood and four in death. I tried summoning both a Barbed Devil and the undead fiend (I suck with names), with no success. Mound King worked fine.

[Morkilus]

You need three things to use rituals, like the barbed devil: researched the spell, meet the path requirement (as selected in the pretender) and enough blood slaves in the laboratory stash as listed in the spell. For battlefield spells, you need that number of gems or blood slaves in the commander's gem inventory (click on the rightmost inventory slot to assign).

[UninspiredName]

As I said before the caster's 5 Blood and 4 Death, Barbed Devil appeared under my ritual list, and the Blood Slaves were equipped to my pretender.

...Just making sure, you don't require more than 14 slaves to cast Barbed Devil, right?

[Nerfix]

This is strange.

[JaydedOne]

The blood slaves were equipped to your pretender?

Try dumping them back to the lab and casting the ritual that way. I don't believe (though I could be wrong) that you can cast ritual spells with components in individual inventories.

[UninspiredName]

Oh, that would explain it. I didn't actually do anything with the slaves after the Blood Hunt. I'll go try that out, thanks!

[Shovah32]

Yes, you dont equip the gems/slaves to the mage to cast a spell. Easy mistake to make though.

[JaydedOne]

And welcome, btw.

[Archonsod]

IIRC the blood slaves need to be in the lab stockpile rather than the pretender to cast a ritual.

The pretender's inventory is only ever used for spells cast in actual battle. Anything cast from the strategic screen uses the lab stockpile.