Eh, funny game. Spells are as follows - gem order does not matter, only quantity.
3 Red = Fire attack
3 White = Thunder attack
3 Blue = life (heals 25 hp)
Red + White + Blue = Instant death
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2 Red, 1 White = Bigger mushrooms
2 Red, 1 Blue = Shrink enemies
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2 White, 1 Red = Speedy progress
2 White, 1 Blue = Freeze
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2 Blue, 1 Red = Slowdown
2 Blue, 1 White = Score double