Mulligans
General Mulligans
Mana Wyrm is always a must keep it generates a lot of early game value and can easily trade into any small minions ran in aggro decks and it can put pressure on on the slower tempo/control style decks.
Babbling book is okay to keep as it is the only other 1 drop minion and can provide you with answers you might need in the early game.
Frostbolt is a good possible card to keep in hand if in a mirror match to take care of a Mana Wyrm or Arcanologist that would otherwise be left on the board, it also does a good job of slowing down the faster decks even if it doesn't kill the opponents minion it will freeze it and give you another turn to come up with an answer.
Primordial Glyph is just an incredibly flexible card and might be able to come through with an early game AoE or can set you up for later turns.
Aggro Mulligans
Mana Wyrm, Frostbolt and Primordial Glyph are explained in the general mulligan section and against aggro carry the same qualities.
Arcane Missles should only be kept in a match up against aggro decks that usually play 1 health minions on turn 1 (Pirate Warrior or Face Hunter). Arcane Missles could be the difference in the opponent having 2 to 3 minions on board with a possible future buff or having 1 or 2 and can even clear the board entirely with the right amount of luck.
Frost Nova should only be kept against minion heavy decks like Token Druid, it will give you an extra turn to deal with the minions and that could be the difference in winning or losing the game.
Combo Mulligans
This would be the mulligan strategy going against combo decks like Quest Rouge.
The Mana Wyrm, Frost bolt, and Primordial Glyph are covered in the other sections and should always be kept if possible.
Arcanologist and Counterspell are incredibly good to have against combo decks like quest rouge. Arcanologist can help you get that Counterspell into your hand and Counterspell itself can make it more difficult for the Rouge Quest to be completed. Best case scenario they play the Crystal Core right into counterspell and that wins you the game, even without that though hitting a Preperation or Mimic Pod could severely set them back and end up turning the game in your favor.
I have been playing this deck for a little while now and I have about an 80% win rate. The deck seems to always have answers to aggro, control, fatigue and any other deck you might run into.
As of right now I am 12-2 with this deck in the area of rank 10-5 in standard ladder. It is definitely worth giving this deck a try.