Help - how to block a gaming website?

I need to block the app Brawl Stars. Are there specific IP's I can target and what are they?

I have a NowTV router which is hardly sophisticated at best but can anyone help? I've added "Supercell" "Supercell.com" & "Brawl Stars" to the block list, is there any more I can do? Exam season, I'm desperate.

Thanks