Question for all: what are best sinergies of and why?
The best synergy according to strength is, of course, Disco-Blackhole. It counters most Monos very badly and, due to BH, also Rainbows have their problems unless they can get an early Sanc or lots of damage out. Here, there is going to be a difference between sharded and non-sharded: With SoF, even Sanc's can't hurt too long, but rush decks can use the gotten time to set up enough creatures. Stalls, on another line, usually have very good chances in countering Disco-Hole. Sancs, again, but also healing against little-to-medium damage output as well as CC can take care comfortably. CC is able to take care of SoF as well when drawn early, that DBH can't pack too many without hurting either early denial or total damage.
Now it is gonna be hard, as there are a lot of good synergies. One is Gravy-Time for sure, as Momentum-Dunes with RT can break stalls if poison is done early with Charger support. However, you can also make a stall version with either Armagio or Otyugh (mostly depending if unupped or upped). Another thing to notice are Pharaoh/Scarabs. If sharded, SoF is gonna take the part of PC
needs so much. Gravity Pull is an awesome combo with SoF, but even unsharded or without a SoF on the field, it can take good care of creatures until your army is up. Chimera as a finisher is a good thing against Dims and high-DR-shields. There are more toys to play with Catapult and Acceleration, if you wanna go heavy stall-breaking.
For 3rd, it's close between Aether and Life (ha, you have sth. in common). While Aether brings Fractal for Guards and Chargers with the help of Dims, Life can bring Mitosis, Adrenaline and Heal (more time for setup is a good thing). All in all, due to CC being more common than Nightmare, Aether is gonna take the win at this point (but not in war, sorry deuce/Zawad
). Fractal Chargers is considered - for good reason - to be the best stallbreaker in the game, while Fractal-Guards bring good speed and CC-resistent creatures. Dims and Lightning are good support cards to ensure you are gonna live long enough.