Senaric's page

Probably out of your price range, but look up Rune of the Inscrutable One.

I wouldn't do the Sihedron ritual thing unless the PCs are known for being greedy, because otherwise their souls wouldn't go to the Runewell . . .

They're adventurers. It may not be their prime sin, but I betcha it's on the list.

Have the cult try to capture them instead. Adventurers are prime candidates for the Sihedron ritual, but you have to tattoo them first. Once caught and restrained, they could be left with only a couple of guards until Iron briar can get loose from his court duties. Just imagine their faces when they realise what their shiny new tattoos are for later on in the Adventure Path.

Some years ago, I was running a 2nd edition game with a guy with a very loose grasp of player v character knowlege. And he read every book he could get his hands on.
One time, the group got into it with a small army of bandits. After several easy kills, a Dispel outs the leader as an ogre magi. When he went down, the rest ran off and there was much rejoicing (and looting).
About a month later they get ambushed. Same ogre mage and friends. This time, my guy runs the corpse through a few times to make sure he wasn't "faking" and glares at me.
The third time, when he finds the ogre mage looting his tavern, he really gets mad. Serious overkill, and he hauled the body out of town for burial. At the time, it didn't occur to me to ask why. But I wasn't about to give up my new favorite toy. With all his game knowledge, this was the first thing he just couldn't seem to wrap his head around.
That ogre mage was a recurring nuisance for a year and a half. My sister's character finally sank the body with Rock to Mud, then dispelled it. I never really got why he was so angry about this. Quite some time later he asked me what was going on with that critter.
It took a while for me to sort out what he was really asking. 2nd edition ogre magi regenerate. But his copy of the Monstrous Manual had a typo, and didn't list that. He could never find any magic items on the body to explain it, and thought some powerful enemy was running around bringing it back to life just to plague him. He just couldn't grasp that what he "knew" could be wrong. I had to show him my copy.