Originally Posted by
Friv
If we're going to rules-quibble...
Vitriolic Sphere is a Level 5 spell, and Z could have an Intelligence of up to 24, plus a magic item. Theoretically, the Save DC on that sphere could be as high as 25.
It is probably not that high; doing that would require him to have started with Int 20 (18 + drow), added Int at every level he gained, and also have a +6 Intelligence-boosting item. But it could easily be a couple of points lower (Int 22 +4 from an item, say) and provide a sphere which Belkar only has a half-half chance of dodging.