Onderzeeboot
Ecstatic Orb
The card is put into the graveyard as the final part of resolving the spell, so no, it can't dredge itself.Is it really broken? I doubt it's better than Brainstorm considering dredge 1 is far less dangerous than dredge 4+ and is also not crazy at filling your 'yard.
Or, wait. Could it dredge from it's own draw?