The deck is effective because:
1. It is mono color and unless a discord it doesn't have quantum problems.
2. It doesn't have creatures, so decks that carry a lot of CC doesn't work against him.
3. It's adaptative versus the size of the other deck. If the deck is less than 40 cards, it means it can use all his strenght only to resist, if the opponent deck is more than 40 cards, it's time enought to save quanta.
4.Unless Jade Shields or Mirror Shield, there is no way to deal against spells in this game, and that spells are strong ones: explosions, fire lances, elixirs.. In other games, you can do things in the turn of the oponnet and play countercards to spells.
5. All the cards works very well together.
I think that nerfing cards is not the solution of the problem. The problem is that the pool of cards in the game i very low, and it's difficults to find synergies and no one of the other elements in his own have cards to deal with all problems like fire has. I think that with pendulum, duo and trio decks will have a big push and new ways of fighting will appear.
And you can play all the AI levels and PVP1 and PVP2, and this deck is only used in pvp2 so nerfing cards make problems to the usual players who grind against the AI.
Also I don't understant that crusade against the Shards of Gratitude. Shards can be destroyed, and stolen, and at most with 6 , that it is not very usual to have six shards in the board at same time, they heal you 30 in a turn. If your deck is not able to destroy the shards or to do more than 20-30 damage a turn in the midlegame, it is because you are used to win games with early rushing decks that lose firepower when the game last longer. And if all people uses that kind of decks, you can make a deck with mirror shields, protected eternity and kill your oponent of boredom.