The Essence of the Oak

 You have magically assumed some of the properties of the mighty oak you lay underneath for decades. For 2 rounds your AC gets a plus 2 bonus. You are resistant to all types of damage except from axes or fire. Any unarmed strikes from any creature smaller than you are pointless. Any weapon that hits you, gets the Dull condition and has a -1 to its damage rolls for the following round, the creature also must roll a strength save of 10 or above or its weapon is stuck in your armor for 1 round.