From publisher blurb:
Legendary items are those that are picked up by the untested adventurers who eventually become heroes of the ages. Unlike traditional magical items, legendary items grow with the wielder, becoming more advanced as new abilities are unlocked over time. In this installment of the Psionic Items of Legend series is the Heartstaff, a legendary version of the iconic psicrystal staff, which further augments the abilities of the psicrystal companion of many manifesters.
Within this short book you will find the history of the Heartstaff, the requirements to attune a character to it, and the abilities of it. In addition, the rules of legendary items are detailed.