What it does
I'm not familiar with "Prismatic Gallery" as an official Magic: The Gathering keyword or ability—it doesn't correspond to anything in the comprehensive rules or any printed card mechanic I can verify. It's possible this is a misremembered name, a card from an unofficial or custom set, or something specific to a particular playgroup or platform.
If you're thinking of a real mechanic, you might mean something like Prismatic (older multicolor-matters references), Converge (effects scaling with colors of mana spent), or a specific named card. If "Prismatic Gallery" is a custom or homebrew card on Mythicwyrm, I'd need its actual text to explain it accurately.
Could you share the card's full Oracle text or confirm the exact name? I'd rather give you correct rules guidance than invent how a nonexistent ability works.
Iconic cards with Prismatic Gallery
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