I don't see how this shield is OP. First, you need 7
to play it. Then, lots of small creatures AND
to keep growing it. This can be done in a Gravity/Fire duo (sacrifice ash eaters and/or photons, graviton firemasters for damage etc). However, if you want to protect it, you need to include a third element... and trio decks are hard to pull off.
So just go rainbow, they are easy enough to pull off, 7
will be gotten sooner or later, and
needs only an Elite FFQ to work in rainbows, which generates the creatures to sacrifice as well.
Actually, rainbows are much harder to pull off than you claim, either because your towers decide not to give you the quanta you need, or your deck decides not to give you key cards (not to mention that sundials can be destroyed by anything with PC)
Anyway, I completely disagree that this is OP, I was just giving an option if it does turn out to be so (which I doubt). I think this would best be compared to bonewall, if you're putting it in a rainbow- bonewall blocks 7 attacks completely plus two more per death. One usually wouldn't play bonewall without fire storm, otyugh, and/or sundial close behind, so you've got more charges coming. Usually, once you've got FFQ, druid, one or two otys, boneyard/wall, and eternity out, your bonewall is too high for even a full board to clear- so is bonewall OP? Bonewall is weak to swarms and epinephrine- this shield is weak to growth, ablaze, and PC. PC is easy to deal with- but what would you do against a quinted forest spirit, fire spirit, or lava golem? I might remind you that quinted lava destroyers are common in decks like CCYB, and Elidnis has a habit of quinting spectres. While I agree that this shield could be powerful, you'd need alot of healing to stop yourself from being killed right after playing it, and it takes a long time to get set up. And, of course, there's the universal shield weakness to momentum (though that can be dealt with in several ways)