Part of Millennium Giant crossover, has Superman numbering triangle on front (1998-15.1). Millennium Giants crossover Continues in Challengers of the Unknown #15 https://www.comics.org/issue/61597/
Aquaman; Cerne (A Millennium Giant); Dardan; Deep Blue; Dolphin; Koryak; Nuada; Nuliajak; Spought; Superman Red; Tempest; Triton; Vulko
Synopsis
Cerne, a Millennium Giant, is headed towards Thierna Na Oge, and nothing Aquaman or any of his friends do can stop it. It destroys the city, but Spought saves a little of the mystic power so they can rebuild.