"...'Lex Luthor Jr.', gathers pieces of the 'World Engine', an ancient piece of 'Kryptonian' alien technology revealed in "Man Of Steel' and uses it to synthesize 'Kryptonite', while the body of slain alien 'General Zod' has tissue extracted to create an enemy capable of defeating Superman.  There is also a scene when 'Batman' breaks into 'Lexcorp' to steal the kryptonite. 

"The enemy created by Lexcorp is 'Doomsday', a monster who killed Superman in DC Comics' 1990's "Death of Superman" storyline..."

'Batman v Superman: Dawn Of Justice' is written by Chris Terrio, from a screenplay by David S. Goyer.  Cast includes Henry Cavill as 'Superman'/'Clark Kent', Ben Affleck as 'Batman'/'Bruce Wayne', Amy Adams as 'Lois Lane' and Laurence Fishburne as 'Perry White'.  Also starring are Diane Lane as 'Ma Kent', Jesse Eisenberg as 'Lex Luthor', Ray Fisher as 'Cyborg' and Gal Gadot as 'Wonder Woman'/'Diana Prince'.