5 turns is too long. I think 3 would be good. I know I sound crazy, but look at the closest thing we have to this.
Miracle.
At three turns, unless your opponent is doing more than 33 damage a turn, it is no better than miracle. Miracle essentially prevents up to 98 damage (or more depending on if you are raising your max hp) this has the potential to prevent much more though, and isnt as practical in as many decks, OR as many situations. Against bolt decks this card is useless because all an opponent has to do is not use bolts for a few turns. So this card is great against rush decks, meanwhile, stalls wont have too big a problem with it.
It can also easily backfire on you if your opponent has PC. Unless you have a nova in your hand, you wont be able to ensure this card isnt destroyed by a PA.
Now for how it is too good...
the free casting cost is way too OP. any non pillarless deck could use this. "But it will drain all your quanta" you say. Yeah, and you have x amount of turns to get it back. as stated earlier, 5 is way too long. Perhaps 3 turns.2 might work as well. No less though.
How I would change it...
SoS
All healing and damage done to you is inverted for 3 turns. Consume all of your non
quanta each turn.
Now 1 question... are your opponents creatures effected by shields as normal while its active? Antimattered creatures arent, so Im assuming they wouldnt, but im still curious.