So there is currently no way to counter the OP card,
Snip,
There are lots of ways to counter Sofo; quanta denial (Discord/black hole) creature control (Bolts/RW/Gravity Pull/Oty) and hard counter (PA)
Back on topic, just banning stuff is never the answer, even though I could scream after seeing 10 plat decks in a row with either 1st or 2nd turn Sofos
quanta denial doesn't really stop it though. The trouble is, even though it costs 7|6 to cast, the fact that the cost is rainbow makes it easy to just use a nova or immo to pull one out.... Current quanta denial methods are useless against that. Its one of the hazards of making high
cost cards.
Creature control helps, but you basically get 1 turn to do it. After that you have a 16 hp permanent chewer on your hands.
RW and GP don't really help that much. In fact they can make it worse if you time them wrong.
Oty can help if it gets out first, but a 'bow or nova deck can get these out well before you can pull one out.
The only reliable counters are PA and Lobotomizer (only if it comes out first though) or mind flayer... the fact is though, these are not viable in all decks. Hence the phrase "just because a counter exists does not mean a card is not OP".
One of the big problems I see is that giving it a high
cost really only promotes its abuse in 'bows and nova decks. Best nerf for this, in my opinion, is to make the card more painful and difficult to use for 'bows and nova based decks.
For example, add an activation cost and have the skill drain 1 of each quanta type when used.