Bringing Walls 1st Barrels 2nd

[Winter]

How exactly do you plan for this to be achieved? Are we supposed to code it so that people bring in those supports on those waves? What about people that need barrels earlier in the game?

For the backup support idea, the backup support switches to the backup after you are out of tomes/barrels (max 2). There is no max for walls, so you would never be "out" of them.