InvincibleMin and Max

Official maps use "InvincibleMin": [-1, 0, -1], to make the bottom layer of the map invincible.

There is no way to make an invincible border around the map using InvincibleMin/InvincibleMax.

WORKAROUND

To make an invincible border, use a duplicate index with the invincible block attribute for every index in the invincible border.

"InvincibleMin": [ -1, 0, -1 ],
"InvincibleMax": [ 1, 0, 1 ],