Scroll of Increase Power
What if there was a semi-rare scroll that when used increased the spell levels used by and/or MP cost of a spell, but also made it more powerful (without significantly changing the effect); like bumping B.Magma to level 7, but increasing the damage; or bumping Spammals to level 3, but raising the summon cap and letting it draw orange/green rats at higher spell power?
Wouldn't be compatible with all spells. Scroll would be as rare as amnesia and the core concept is...you like the blinding spell gimmick that "Dazzling Spray" has, but it no longer really does any damage and is just a blinding spell. Use this to make it more easily blind stronger things and do more damage, but cost more spell levels and MP. Can only be used on a specific spell once; on may thing it effectively just raises the power cap (causes damaging spells to do more damage and hexes to pierce more MR); on summonings it either summons more or more powerful things of the same class, etc.