A nonmagical wall of bark erupts from the ground to protect you and your allies. Choose a space in front of or behind you. The wall forms in that space, extending 15 feet out from that space along the ground in opposite directions for a total length of 30 feet. The wall is 5 feet high, 6 inches thick, opaque, and provides three-quarters cover to creatures behind it.    If the wall cuts through a creature’s space when it appears, the creature is pushed to one side of the wall (your choice). The wall can’t otherwise occupy the same space as a creature or object. The wall must be vertical and must rest on a firm foundation, such as the ground, the floor of a building, the deck of a ship, or similar.    The wall is an object made of bark that can be damaged and thus breached. Each 10-foot section of the wall has AC 15, 100 hit points, and vulnerability to fire damage. Reducing a section to 0 hit points destroys it.    If you maintain your concentration on this spell for its whole duration, the wall becomes permanent and can’t be dispelled. Otherwise, the wall disappears when the spell ends.