Kammi
This small green rock is inscribed with the picture of a small building.
When thrown to the ground and destroyed it will magically build a large log cabin with a pointed roof. On the inside it will consist of two rooms. The first contains a few beds, a table and chairs. The second has benches along the sides and a stove under a compartment holding small rocks.
When taking a short rest inside you can add 2 to the result of any Hit Dice you spend.
When taking a long rest inside it you regain 2 extra Hit Dice.