[LintMan]

Originally posted by magnate:

(1b. Are there any ways to acquire gems other than random events and magic sites?)

This isn't a way to acquire *more* gems, but it may help in your situation: you can use Alchemy to convert gems. Alchemy lets you convert from Astral to any other gem type at 2 for 1, and from any other gem type to astral, also at 2 for 1. (So you can go from any gem type to any other at a maximum of 4 for 1 cost). So if you have a big enough surplus of some other gem type, you can use that to boost your nature gems up to the amount you need to cast your spell.