Warning: contains major spoilers for Dark Knights of Steel #4!
When it comes to hybrid villains, DC can be hit or miss, particularly where Joker and Lex Luthor are concerned. However, the newest combination of the two within Dark Knights of Steel #4 succeeds where past versions have failed. Batman and Superman's nemeses CAN be an effective amalgam, when used to their full potential in their hybridized form.
Superman/Batman #61 from 2009 has the creative team of Michael Green, Mike Johnson, Francis Manapul, Brian Buccellato, Rob Leigh, Adam Schlagman, and Eddie Berganza. It featured an amalgamation of Lex Luthor and Joker, but it was a rather poor version. This was largely because the combo was a front for Doctor Destiny and wasn't actually a true dual villain-made one. The opportunity to let these villains be at their worst together was passed up. However, DC recently tried a new iteration and it's the best yet.
Dark Knights of Steel #4 has the creative team of Tom Taylor, Bengal, Arif Prianto, and Wes Abbott. This series places Batman, Superman, Wonder Woman, and other popular DC heroes in a Medieval-inspired fantasy world. The "Green Man" is responsible for the death of Jor-El, a ruler in the House of El. He is a brilliant combination of Joker, Lex Luthor, and Green Lantern—creating a truly evil villain worth fearing.
The Green Man begins his life in Dark Knights of Steel's universe as part of the court of the kingdom the Els would eventually rule, with the name Alexander Luthor. He fails to provide warning about impending doom from a nearby volcano, which the Els protect everyone from. He is banished and finds a Green Lantern ring, which he takes and gains power from. As a result, he also loses his sanity, becoming a trifecta of DC villainy. He has now returned to exact his revenge and thus far, he is succeeding.
This version of a Lex Luthor/Joker hybrid is much more impressive than past attempts to combine the two. In the case of Superman/Batman #60 and #61, it is quickly revealed that Doctor Destiny is behind everything happening. This significantly lessens the threat that the titular heroes face. Joker and Lex Luthor are two of the best villains in Superman and Batman's rogue galleries, which makes the pairing interesting right from the start. It combines the worlds of the Dark Knight and the Man of Steel to create a superior single foe. However, to rise to that level, the duo has to be taken seriously as that entity and used effectively—a feat which only Dark Knights of Steel has succeeded at thus far. DC can create some incredible mash-up villains and heroes, such as in the case of the Green Man with the Joker and Lex Luthor, but they have to be well-utilized in order to reach their full potential.