The short version of it is that there is a balance between how much time (read: mana, turns) one can spend accruing cards while contributing to the battlefield
Creature - Vampire Shaman Color tag templates(None) Serra Avatar Serra Avatar's power and toughness are each equal to your life total
Here, my opponents decision to cycle a shark in to block my Familiar was punished by this sequence: play second Oven, sac second Familiar to get my third food, reanimate Feasting Troll King, cast Great Henge for just two mana, tap it to cast Uro and trigger Henge, sac Uro to second Oven (with his triggers on the stack) for two more food, use food to reanimate both Familiars (two more Henge triggers)
Its probably about to really pop and if a win condition like this makes Apostle (because you tutor for demons) more attractive than Rat Colony, people could build both decks (probably not) or build the older Shadowborn Apostle build which has upside if there are older cards in it
Even partners with inherent synergies or partners that are dependent on each other contribute to this problem
These packs are Mono-White, so while there's definitely a few usual suspects not seen here, there's a lot of great stuff to work with