It's funny with all the bullets on the ground and destruction of Lexcorp, many of us assumed it meant Doomsday escaped from research containment lab. It kind of is a bummer that he wasn't created as a fail safe device against meta-humans. Could have worked in a Waller cameo as well, and would have worked between films in the DC universe. Lex having worked with the government or something for its creation would not have implicated him either. Instead they waited till end of the movie and had a mess of Lex interrelate to Martha, Lois, Superman, and Batman. Doomsday was the backup if he couldn't force these 2 heroes to destroy each other.
Let's say his plan worked by the way. One of them would have died presumably right? That means he does not end up killing both heroes. One way or another he'd still have an enemy left over. Was he just on team Batman then and counting on Superman to lose? From what I remember he did seem to smile or something when finding the [blackout]batarang from stolen kryptonite right?[/blackout]
You don't understand Lex and what plays a part in his motivations. This version of Lex is psychotic, in a similarity to the version of Joker played in Nolan's TDK. Lex was not concerned about sharing Doomsday for the protection of the work. He doesn't play that tired old game of pretending to do something for world interest but really just for his own. This version of Lex is more layered and psychotic, so kind of like the Joker where he just wants to watch it all burn in a way. He hates Superman, so Doomsday was created specifically for that reason. Lex wants to get rid of the God of Krypton. That was his endgame. This version of Lex has plan A through Z. He always has another backup plan. All Doomsday was, is the backup plan if his primary did not work. A fail safe device actually sounds ridiculous! Oh let me create a monster to kill all metahumans No....