Q: Does a Spellcaster allow to you put a Spell back in your hand any time it would normally go on the discard pile, or only if you’ve used it for one of its powers?

A: To refresh, if you use the one of the Spell Actions (Invisibility, Healing, or Fireball) while you have a Spellcaster in play, you can put the Spell back in your hand (face in) after use, instead of on the discard pile. However, this is NOT because the Spellcaster protects it from discard somehow. It’s merely meant to convey that having a Spellcaster lets you use a Spell again another time. For any other discard situation, it’s just discarded.