Mr. Impossible and the Rainbow is a story from the 1982 Annual.
Plot[]
Mr. Impossible can do ANYTHING!! From jumping over a house, to hovering in midair, to reading a book without looking at it. One day, he met William as the latter was coming home from school. William was bored and wants some excitement. Mr. Impossible complies by jumping over a haystack! Impossible! Mr. Impossible then shows William how he can fly like a bird. Impossible!
Mr. Impossible sees a rainbow in the distance and takes William along to slide down it. Taking William by the hand, the two fly up to the rainbow, sit on a cloud that was floating by, and they slide down the rainbow! Impossible, but fun! William, feeling much better, thanks Mr. Impossible for the fun and heads home. Mr. Impossible heads home too. Disappearing in front of William's eyes. IMPOSSIBLE!