Except from this article :
What are you most excited about with the new edition?
I love having eight factions to work with. They each have a unique personality that we’ll explore in the weeks ahead with the faction previews. Deckbuilding is new and exciting – instead of a gold penalty, players can now run a primary faction and a banner agenda that lets them ally with a second faction. As a result, the number of potential deck options has exploded.
if i read this correctly then 1 CORE SET is enough for casual play amongst 4 friends because each PLAYER can pick up to 2 factions and the combination of strategies would be endless
CORE contains
--------------------------
Stark
Lannister
Targaryan
Baratheon
Greyjoy
Martell
Tyrell
Night's Watch
so you can have a combination of (but not limited to)
---------------------------
Stark-Baratheon
Lannister-Targaryan
Stark-Night's Watch
Lannister-Tyrell
Greyjoy-Night's Watch
Martell-Greyjoy
Baratheon-Lannister
... well you get the picture...
I imagine that would also be applied in tournament rules? (never played in tournament... im just a new casual gamer)
and if thats not enough then we can talk 2 Core then...