With one core I would just do Kingslayer. Smash two factions together and add 10 neutrals.
Ten neutrals? Three coalitions get 7 and one 8; none 10.
As Robert said, you could use the Kingslayer format (example decks are listed at the back of the Learn To Play booklet.
Or if you like the short game ("Introduction Mode"), no deck building is required anyway because you just take the 20 faction cards and add neutral and plots.
That's what I asked for. I want to play the quick games, so I'm asking about decklists of the neutral cards and plots in a 1v1 short game.