Board Thread:Supergirl discussions/@comment-31722073-20190520131713/@comment-31722073-20190607005921

Malefic was specifically brought in by the Monitor, presumably for the same reason he brought the Book Of Destiny or funded villains in the comics, to test them before the Crisis. Leviathan is independent from the Monitor and set up the villains of the whole seasons, they wouldn't be defeated in 9 episodes, especially not shared with some other group.