WARNING: Spoilers ahead
Pages 1 and 2
Page one of the HellRealm Picture Book explains that what appears as three flower heads in the ground, really is a Coblynau surrounded by two Mandragores. Those folks always spawn it this combination.
Pages 3 and 4
Page four of the HellRealm Picture Book refers to a strategy of defeating Morallta/Beagallta. The Book instructs to attack Morallta/Beagallta with Coblynau while he is fully visible, and to attack Morallta/Beagallta with Cait Sidhe while he appears as a black silhouette.
Pages 5 and 6
Pages five and six of the HellRealm Picture Book refer to a strategy of defeating Yama, the folklore residing the HellRealm. In the first stage of the fight where Yama is appearing in mirrors, the Book instructs to attack him with Fomoire. In the second stage of the fight, when Yama is closed inside of dark ball /orb, the Book instructs to attack him with Beithir, and when the ball/ orb vanishes, to attack him with Morallta/Beagallta.