The Champions of Kamigawa heroes are cards that represent that journey from average joe to Legendary Creature; they flip around and become their Legendary, more powerful selves. To show this progression the hero cards actually flip upside-down -- which means their art needed to be able to flip, too.
That makes for an interesting challenge for the artists.
Let's look at a sketches of the hero cards. Here's the art description given to Kev Walker for Budoka Gardener:
Location: Not important
Action: This is a brand new special "flip" card. The art has to show the before and after stages of a character. The "before" stage should show a skinny human monk student who worships the earth. The "after" stage should show the same monk, much older and stronger, as a grand master monk who has the power to turn the earth into a powerful elemental.
Notes: The art box has a special size: 2 1/16" wide x 1 1/4" tall.
The creative team provided artists with an example to suggest the composition of the hero cards. You can see that the aspect ratio is a wider rectangle than you see on a typical Magic card.
Except for the removal of the swords at the belt of the "after" stage (green monks are not the katana type), the final art is composed the same as the sketch:
You can see that the piece is equally beautiful when flipped around and the meek gardener becomes a Dokai, Weaver of Life.