Ambassadoring 2 copies of a card that I want to have myself, just to get the piles back up & delay a 3-pile.
nostalgia
that log... so cool. 41 turns... ambassador war lasts 26 turns, then stef buys a curse to continue it... (and because he needs to stop rabid from continuing to green as well as give him negative points)... but when Rabid moves for the three -pile, and stef is 30 points behind and is a little bit away from getting a colony a turn, he ambassadors all his FG back to the supply... and then later some mining villages.
I've had the buying a curse and ambassadoring them all to my opponent thing win the game for me multiple times, but this is just a whole lot cooler.