I don't think it needs to be nerfed. You need a lot of cannon-fodder to power it up, and the battle needs to be stable enough to give you time. WIth the dragon, it was possible because it has amazing numbers of those blobs with it. Sparks tear through the blobs by dozens and the HP grows nicely. In hectic situations, it's not very useful.
I would keep it as it is just for "coolness".