Putrefy uses Golgari guild magic to accelerate the decomposition process to the extreme, causing a creature or artifact to become a dry corpse or broken shell in the blink of an eye. And Jim Nelson's art definitely gets that across:
The art depicts a hapless wizard being struck by the spell, and he is indeed missing an eye due to the spell. At card size, though, it may be hard to tell that the blue orb to the left is not the wizard's missing eyeball. Here's the enlarged art:
The eyeball has popped out just above the eye socket. The blue orb is actually a talisman that used to be around the wizard's neck: it, as well as the wizard's now-tattered robe, serves the useful purpose of showing that Putrefy can "decompose" artifacts, as well.
Now you know -- and knowing is half the battle.