Bifrost: Can't upgrade militiary tools unless you own the building
I swear this was not the case before the definitive edition. Other than any military building you start with, you can't ever upgrade the mliitary tool unless you are the one that chose the building as a reward, eg. You are the one that has to actually build it for your friends.
Meaning: Player 1 chooses Warrior camp as a reward after the first winter.
Player one builds a military camp.
PLayer one one upgrades the tool for Warriors.
Player 2 asks Player 1 to build them a military camp and gets it built.
Player 2 can not upgrade the warrior tools. Ever... Never for the entire Bifrost.
We used to play and it didn't matter who took the military building as once it was built in your territory you could upgrade the tools. Now you can't.