Valentine Pontifex is a novel by Robert Silverberg published in 1983.
Valentine Pontifex is a novel in which the Metamorphs try to drive people from their native world of Majipoor by spreading ecological hazards.
[1] Dave Langford reviewed Valentine Pontifex for White Dwarf #56, and stated that "Readers will remain in any agony of suspense unless they've cheated by reading the book's title.
Not many surprises, then; but if you liked the previous two you probably won't be disappointed.
"[1]