The Michael Moorcock Library: Erekose: The Swords of Heaven, The Flowers of Hell Vol.1

In this story Erekosë assumes the role of "Clen of Clen-Gar," a noble of the land called the "Dream Marches", part of a greater land called "Heaven". He befriends a peaceful race of beings known as "Angels", who can best be described in one of their forms as flying manatees. In the day-time, they gracefully float through Heaven, absorbing water vapour from the air, and by night they release the stored water as acid rain upon a neighboring land coincidentally called "Hell", whose savage inhabitants live in poverty compared to the luxury of Heaven and the Dream Marches. The angels can also assume an insectoid form similar to human sized ant-men.