I see requests quite often for 4 player decks for people to play with their friends. Now that Dori is released, it's possible to put together 4 mono-sphere Dwarf decks (with Spirit getting the short end of the stick when it comes to the heroes), where the entire field gets boosted from Dain. These decks purposefully require only a single Core Set, but could be improved with more.
They also require pretty much the full card pool, and could again be improved by having an unlimited pool (putting 3x Battlemasters in both the tactics deck and the Oin deck, for example), and I realize anyone with the full card pool is probably capable of putting together 4 decks on their own, maybe they want a starting point.
I think these would be really fun to play, but are currently untested and welcoming suggestions.