Although swindler and spy were alot more powerful than usual because its possible to actually help ur teammate
I think you'd want to make attacks vs. teammates purely optional, with turn-by-turn discretion for the affected player. There's lots of times when an attack is useful, or when a reaction is useful, and those wold be very good strategic tools.
shared native village mat would be wacky...
Yes! And more in that vein:
Since the two players are one "team", then what if
duration cards affect your partner, AND only last through your partner's next turn? Your Tactician discards your hand, but SHE draws five on her next turn. Your Lighthouse only lasts until her turn, then it's out of play, and discards into HER deck! Your Haven passes a card to her, you set aside a Horse Traders and she picks it up.