Given the number of transfiguration lessons the card that this spell debuts on in the TCG requires in order for one to learn it (and the context it is mentioned in the Harry Potter and the Philosopher's Stone) this does not appear to be very advanced magic (probably second or third year level).
There is another spell which transforms teacups to gerbils. It may even be essentially the same spell, but with a slightly different end result, as both animals are rodents.
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