The element that destroys Marina (in VN's novel Ada, 1969, Van's, Ada's and Lucette's mother who dies of cancer and whose body is burnt, according to her instructions) is fire:
Numbers and rows and series — the nightmare and malediction harrowing pure thought and pure time — seemed bent on mechanizing his mind. Three elements, fire, water, and air, destroyed, in that sequence, Marina, Lucette, and Demon. Terra waited.