What would you suggest to replace the Nymph... if one doesn't have it, I mean? 
I'd take Gravity Force because it synergizes well with SoFo.
a black hole would be better in my opinion. the idea is to deny the opponents quanta so he cant play any creatures. in the case he can play (some air and fire rushes) them you can always use antimatter. i find gravity force somewhat unnecesary in this deck, the black hole would heal and add some more lockdown if you dont have the nymph
That's also a possibility but I figured since he already has 4 BH, a Nymph and 5 SoFo's that can become a BH (which makes a total of ten if we count the nymph once) that those should be enough. My second choice would have been a gravity shield because it doesn't affect you a lot. You have so much PC with SoFo's that even if it gets stolen it doesn't hurt you.
Another advantage of Gravity Force is that it allows reusable PC because of the HP loss. So besides the stalling you already have, you can take down towers much more efficiently.
