If it returned to the battlefield, it'd be a better Bloodghast. By, like, a lot.
Ravnic, I'd test it out — it is definitely one of those cards where you want to discard it for value at least once before you actually play it, though. So I'd say that it's excellent in an Artifact/Madness deck (since it gives you a card you can repeatedly pitch for value that turns into a 4/2 when you're in the clear), OK in an artifact/dredge deck (sometimes you'll "draw" a 4/2 while stocking your graveyard), and bad in an Artifact/Sacrifice deck (4 mana for a repeatable sac target is expensive).
Ravnic, I'd test it out — it is definitely one of those cards where you want to discard it for value at least once before you actually play it, though. So I'd say that it's excellent in an Artifact/Madness deck (since it gives you a card you can repeatedly pitch for value that turns into a 4/2 when you're in the clear), OK in an artifact/dredge deck (sometimes you'll "draw" a 4/2 while stocking your graveyard), and bad in an Artifact/Sacrifice deck (4 mana for a repeatable sac target is expensive).