(I know I'm gonna be beaten up for posting this, but well...)
Well, first of all, is eating 3 permanents then die really that OP? While pulvy is long lasting, this shard implodes automatically. As opposed to pulvy, it has no attack as well, and provides wee rushing and stalling power. Its sloe use is to destroy permanents, which is like an insurance. If your opponent doesn't play any perms at all or does not rely on them (or have so many pillars that SoFo can't do much), it's basically a dead card. If you use it outside of gravity, it is even more dead-the BH go waste (side note, upped SoFo gives unupped BH, intended?). It is only powerful in the sense that it helps breaking stalls by smashing perms. For the pillar smashing part, looks at EQ... it is way more versatile but fail to perform specific duties. Once again, it's an insurance in case you see mono-aether or other perm-heavy deck types (including stalls, which would have included PA for important perms anyways). Other than reducing the power of perms (which is quite high now IMO, or else why do we need all those pulvies in non-DBH speedbows, steals in rainbow DBH, explosions in immorush etc?), which is completely fine to me, it only provide a BH with 3 turn delay... (sounds so much like event horizon to me XD) OP or not?
Secondly, you know, most of you think that it provides a cheap way out for all elements to have PC, but... no. Remember it's 7/5 in cost. It's either nova+SoFo or SoFo consumes effective quanta. The former one is a 2-card combo, and deserves to be more powerful than a single pulvy (2 card combos like oty+quint could have won you a game, for comparison). The latter one uses up your quanta which could have used for summoning mid-rangers that could deal 20+ damage (for instance, GotP, costing 6
unupped, deal 28. the value is underestimated due to potential CC.) while SoFo is active, assuming SoFo really destroy 1 perm each turn. By using up a card slot in your deck for SoFo, you essentially gave your opponent a heal. Let's compare this to upped oty. For around the same quanta cost (and slightly higher activation cost of oty ability), oty guarantees death of all your opponent's creatures which are not protected and has lower than 5 hp (and more due to growth of oty, underestimated again), but for a cost slightly lower cost you can smash 3 perms. OMG! 3 perms! It can occasionally win you a game, but never as frequent as oty. Sure, oty is for gravity only, but other elements have similar cards that uses quanta way more efficiently than SoFo. Putting a pair of SoFo in every deck actually impedes the speed, while "smart" novas waste card space or conflict with other uses of your
quanta.
Thirdly, it enriches the metagame. GP+SoFo, another 2 card combo, is a very effective synergy. The BH is situational, but nonetheless, powerful. Instead of turning it into a BH, you could have catapulted it for massive damage or accelerate it to bring doom slowly. It even encourages the use of mono-gravity, which increases the variety of the metagame. It also enables a lot of fun synergies by compensating their lack of PC, compromised by deck speed, which is a fairly fair trade. It gives rise to alternative ways of deck building, which adds to the fun of the game (and more topdecking chaos!). It has good enough reasons to stay the way as it is.
One might argue that SoFo is OP by comparing it to BE and/or pulvy. Yes, it's much better than BE, so what? SoFo is something between instant PC and chronic PC. It does not give as much guarantee to the complete obliteration of stalls than pulvy/BE, and usually needs multiple copies to work. However, in comparison, drawing 1 BE/pulvy is enough to break lots of stalls given enough quanta is produced (by proper deckbuilding skills of course). They are not exactly of the same genre, and so, arguing that SoFo is not element specific but cost roughly the same (or even less) to destroy perms is not valid, as the perm destroying power is much weaker unless multiple copies are used, which, again, is related to card advantage, and let me remind use all once, 2 card combos deserve to be better than single cards. Well, but, BE is a 2 card combo too. However, BE is better in terms of PC for mono-entropy, and is more of a guarantee, as said above. Overall, SoFo is not much better than BE and is comparable to pulvy, and it's BE that needs a buff IMO, not SoFo needs a nerf.
In conclusion, SoFo is not OP, but just quite powerful. It weakens perms, which changes the metagame in a good way, and balances the nerf to rushes by nerfing SN. It is a semi-sustainable form of PC only, is is powerful, but not OP. I know this is against the general consensus, but ah well...
*Gets ready to be decapitated*