For me the greatest inspiration from Vance wasn't the magic system, but his great characters, I wish I could create such fun npcs like Cugel for the game.
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It was a big mistake to change to the names of old spells in Spell Compendium. Also don't forget Ioun Stones, the real ones should be made from stars, or found in the Minerals, those made by the Netherese are cheap imitations. I wonder about the Overworld, what type of plane is it..