Artwork is an easy 4. In my book, a 5 is reserved for blatantly godlike art, and armagio's art is more or less perfect, just not the raw quality that would be expected of a 5.
The design is cool. It's more than just a pseudo 25HP addition to your health pool that can get RT'd. 25 HP is a good base for cards like Acceleration and Rage Potion, whereas the Gravity Pull can be used as a last-resort method to deal with incredibly hard hitters, as the excess damage doesn't roll onto your HP.
However, 5
is pretty steep for what it offers. In being a combo/contingency card, it either needs to get out early or be able to be played fast out of your hand if it's needed, especially since you need to wait a turn to tank damage. I would reccomend reducing its cost to 3
; It isn't insta-played within the first turn or two, balancing it as a combo card, while being cheap enough to be played as an emergency card, without being so cheap that there are no repercussions to playing it.
Or, a different approach could be taken. Change it's cost to 4
and make it's ability "2
: Apply Gravity Pull to target creature." Now it becomes less of a combo/contingency card and more of a supportive card, which still technically has the ability to GP itself. This would allow things like GPing an opposing creature to get rid of it at cost of face damage, or GPing a friendly SoF for some truly legitimate tanking power.