[quote=DeathstrokeSW]
Is David Cain an Assassin? Also, Richard Dragon, I've heard of him but who is he? I'll at the least consider Killer Moth.
[/quote]

David Cain is League of Shadows/Assassins.

Richard Dragon is a martial arts master who mentored Ben Turner (Bronze Tiger) who joined the League of Assassins and later the Suicide Squad.