[thewriteguy]

So if we assume this could be Wave 3, based on Arkham Knight

1. Batman
2. Two-Face
3. Scarecrow
4. Red Hood (spoiler from the game)
5. Harley Quinn
6. The Arkham Knight

Then Wave 4 could be another TV/movie wave. Perhaps it will consist of:

1. The Riddler (Jim Carrey)
2. Arrow (from the CW series, "Arrow")
3. Deathstroke (from "Arrow")
4. The Flash (from the new CW series)
5. ???
6. ???