Brockalizer
In Superman: Red Son, Brainiac theorizes that it would only take a level 9 intelligence like Lex Luthor a few minutes (14 IIRC) to talk Superman into committing suicide. With that in mind I propose the following tests of Lex's powers of persuasion.
Doom scenario 1: Lex is assisting Dr. Doom with an experiment, the experiment fails, can Lex talk Doom out of killing him?
Doom scenario 2: Lex is working with Doom, makes some minor adjustments to one of Doom's failed experiments and the experiment succeeds, can Lex persuade Doom to spare him?
Xavier scenario: Could Lex talk Prof. X into switching sides and joining Magneto?
Richards scenario: Could Lex talk Sue Richards into having an affair with Namor?
Doom scenario 1: Lex is assisting Dr. Doom with an experiment, the experiment fails, can Lex talk Doom out of killing him?
Doom scenario 2: Lex is working with Doom, makes some minor adjustments to one of Doom's failed experiments and the experiment succeeds, can Lex persuade Doom to spare him?
Xavier scenario: Could Lex talk Prof. X into switching sides and joining Magneto?
Richards scenario: Could Lex talk Sue Richards into having an affair with Namor?