January 2018
Lethal Proliferation, which Lethality gets at Level 12, affects an ability that Lethality doesn't get until level 38 (Toxic Haze), according to the trainer. There is no other benefit to the ability.
Perhaps Lethal Proliferation and/or Toxic Haze should be moved so that Lethality doesn't get something completely pointless at Level 12?
March 2018
I would also recommend posting this in the official Suggestion forums found here for the best visibility and to add more discussion to your suggestion for other players to see.