A 083
Driders cast spells as Clerics, Wizards, or Sorcerers. I can't see anything that says they don't follow the normal rules for those classes: so they cast off Wis, Int or Cha respectively.Spells
Driders cast spells as 6th-level clerics, wizards, or sorcerers. Drider clerics can choose from the following domains: Chaos, Destruction, Evil, and Trickery. The typical spells prepared shown here are for a drider sorcerer.
You may looking at the SLA section that says "The save DCs are Charisma-based.".