Sturdy Tree Fort

You cause a large tree to grow in the 5-foot square you touch. The tree has (CASTERLEVEL*4) feet of thickness, and it can grow to any height you designate, up to (CASTERLEVEL*5) feet high. If there is a ceiling or other barrier overhead, the maximum height of the tree cannot exceed the space available. At any point along the tree's height, you can create a sturdy wooden building that fills (CASTERLEVEL/4) ten-foot cube(s). All portions of the structure must be adjacent to the trunk of the tree (or can have the tree trunk extend up through their spaces), but otherwise these cubes need not be contiguous. If you place the cubes so that they are contiguous, the buildings merge together, complete with ladders connecting different vertical levels. The fort is magically supported, but if the tree it is attached to is destroyed, the structure is destroyed as well (the tree has hardness 5 and (CASTERLEVEL*20) hp). Each building you create has shuttered arrow slits on its walls and in the floor, granting those within the structure improved cover against attacks from outside while the arrow slits are open and total cover when they are closed. Each cube within the fort is equivalent to a secure shelter, other than the size and its wooded construction material (hardness 5). When you cast sturdy tree fort, you can designate (CASTERLEVEL) creatures. Designated creatures gain a +10 bonus on Climb checks and are not denied their Dexterity bonuses while climbing on the fort's structure, as they find handholds and stable footholds easily on the tree and its buildings. You cannot cast this spell in an area of worked stone, though you can cast it in natural surroundings that would not normally support the growth of a large tree, such as a cavern, desert, or glacier. If you cast this spell in a forest, jungle, or similar heavily treed terrain, the fort is camouflaged as long as its doors and windows remain closed (or even if they are open, as long as those within remain quiet and take no violent actions), requiring a successful DC 25 Perception check or Survival check to notice its presence.