Dyzil's Deafening Decoy spell description claims it consumes a peridot. It does not. It consumes a malachite. I ended up with half a stack of expensive and useless peridots and running out of malachite while out hunting. Allakhazam seems to say this has been noticed and uncorrected for over 10 years now.
Yeah, seems the spell description 1679 has a typo. Although, all the sources have Malachite (item ID 10015) listed as the ingredient. And this spell is a "swarm pet" and as all other magicians' swarm pets use Malachite to summon. Prepare to carry around a stack of those.
