I think the change is an improvement, though the card was already okay. The card now differentiates itself from Hope a lot more, since it is based on creature hp, not number of light-emitters, and the cost is cheaper, which reflects the fact that Hope has more raw power in most cases.
Hope also has shroud, but I don't think this card should be given it. (it hasn't been brought up yet, but I figure I'd mention it, since I've compared this to hope quite a bit) In RoL/Hope, you can destroy the rays pretty easily, so having the hope be untargetable isn't overpowered, but in gravity, the creatures are nigh unkillable by damage, so the vulnerability should be the shield, since it's obviously not the huge creatures.
It would be very hard to pull off, but this card would be absolutely hilarious if you could manage to fractal voodoo doll and play this. Voodoo doll has the best hp:casting cost ratio. Then all Pandemonium breaks loose...
