you mean all YOUR creatures or all the creatures on the field ??
The upped does not send attack into the negative.All means all - all of your creatures, all of the opponent's too.
ooops, miss that line.I think -1 attack make a huge difference between unupped and upped. better to be the same effect with a different cost.In my opinion, this card is too powerfull combined with gravity shield, wich spare the same element.
I'm all for Heavy Shield and Chimera buffs (:Though, rather than a spell, I think it's be a nice stackable permanent?