Redemption of the Fallen

Source
This is one of several possible contents from a Sealed Tome found on the ground in Karazhan.

Effect
Applies a buff to the person who opens it that lasts one hour.

Your healing spells have a 3% chance to summon a ghostly ally for 1.25 min. This ally will heal your party for 1286 to 1358.

There does not appear to be a stack limit on the number of allies that can be 'proc'ed.

Contains
Using the book generates in your inventory.