Blessed Prayer Beads

Blessed Prayer Beads is a quest-reward trinket from a Priest-only quest line involving Sunken Temple. It is argued to be the best reward option from that quest (even for Shadow Priests), as the other reward choices (Circle of Hope and Woestave) are easily replaced by gear from instances as low as Stratholme and Scholomance.

Source
Blessed Prayer Beads is a quest reward from the quest Blood of Morphaz. This is a chain that starts with High Priest Rohan (Alliance) or Ur'kyo (Horde).

Effective Spell Power
Assuming this trinket were activated every cooldown, it would grant: 101 * 20 / 120 = 101 * 1 / 6 = 101 / 6 = 16.83 Spell Power