Zamorak page 4

A Zamorak page 4 can be found as a reward from all levels of Treasure Trails.

The page can then be added to a damaged god book received from the Horror from the Deep quest. There are 4 pages in total.

Once all 4 pages are added to the book it becomes an unholy book, which you can then equip in the shield slot, preach from, or use to bless unholy symbols (50 prayer required).