Plate Armor boosts your creatures' health by 3. It does nothing to stop enemy creatures... BB will however delay them for six turns. The only use Plate Armor will get in this deck will be turning your 8|3 Shriekers into 8|6 Shriekers.
EDIT: OK, it's way too early in the morning for me to be posting stuff on this forum. Realized the Armor cards are to make enemies crash into the Gravity Shields.
Looks like a strong deck! Your main weakness will be Momentum, but until you're threatened with deckout, you can rewind such creatures with Eternity.
I don't think Stone Skin is going to be enough healing in most cases. Shards of Gratitude would be a great addition to this deck... and see if you can't trim it down closer to 30 cards. My bad-draw-sense is tingling.