We each used 1 respawn
Air elementals not built, but we have Luna and 2 necromancers, stables, access to a grassy secondary for 50-99 cents, and plenty of gold. I cleared 90 cents with Luna, then came blocks that couldn't be taken without losses without birds, so I turned back to my respawn, which turned out to be gigantic. I gathered gold for birds in the fort, claimed Boots from the secondary, found 3 Griffin Conservatories there as well, was about to take them, but the opponent conceded at max conservatory. Thanks for the game!