Two things are happening.
First: He has used antimatter on your shriekers. That's why their attacks are negative. All damage dealt is returned as healing. I recommend you bury all your shriekers, so they may not be targeted, but barring that bury your antimattered ones to stop their attack.
Second: He has played eclipse shield. This allows him to use one quanta to prevent three damage. This does not however stop healing. As shriekers deal 8 damage, you'll need one non-antimattered (it'll have a positive amount of attack) for every three of his pillars to eventually break the shield.
Stopping this is quite simple. As I said earlier, burying your creatures halves their attack and protects them against antimatter. If you bury them all, then you protect those that aren't antimattered and halve the damage of those who are healing. Use the card quicksand on his pillars to reduce quanta generation, and eventually you'll not only destroy his shield, but you'll destroy any quanta he has, completely halting the deck.