How do you get the Season 2020 - Flex Challenger Icon?
It was a ranked reward. Riot's description in the client reads: “This icon was earned by finishing Challenger in Flex Queue in Season 2020”
Is the Season 2020 - Flex Challenger Icon still available?
No. The Season 2020 - Flex Challenger Icon was a ranked reward. To earn it, you had to reach Challenger in Flex during Season 10 (2020). Riot does not hand out past ranked rewards again, so you cannot earn this icon anymore.
Season 2020 - Flex Challenger Icon is one of the rarest LoL summoner icons.
