This sturdy quarterstaff is formed of living wood, as evidenced by the tender shoots and leaves along its length.

A staff of the unyielding oak is actually a treant bound into quarterstaff form. When you wield this weapon, it functions as a +1/+1 quarterstaff if you are neutral, neutral good, neutral evil, lawful neutral, or chaotic neutral.

Relic Power: If you have established the proper divine connection, you can command this staff to become a treant. This ability functions like the changestaff spell, except that the treant is fully real and can speak to other treants and animated trees. If a staff of the unyielding oak in treant form is reduced to 0 hit points or fewer, it reverts to staff form and cannot be used again for twenty-eight days. The staff can take treant form any number of times per day, but can be in that form for only 12 hours overall during any one day. To use the relic power, you must worship Obad-Hai and either sacrifice a 8th-level divine spell slot or have the True Believer feat and at least 15 HD.

Lore: These staffs, of which three are known to exist, are treants that have willingly bound themselves into quarterstaff form to aid Obad-Hai’s followers. Each willingly serves for a year and a day, after which another treant takes over the responsibility (Knowledge [religion] DC 20).

Prerequisites: Craft Wondrous Item, Sanctify Relic, changestaff.
Cost to Create: 2,500 gp (plus 600 gp for base item), 200 XP, 5 days.