The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

a member of
the Legion of Superheroes,
The Big Bang Theory Season 7, Episode 3

a LEGION of Unsullied
and three dragons,
Game of Thrones Season 7, Episode 2

{\i1}Our LEGION of hackers opened{\i0}
{\i1}a secure and undetectable email account{\i0}
Money Heist Season 3, Episode 5