save up your tokens. you get 10 each day so every week is 70. also in Sundays and Saturdays events happen to get 100 tokens from a limited achievement so 170 is a lot for each week. in two weeks you can get a premium pack witch usually give legendary or have bad luck like me and only give epics. about 5 cards in those chests. and raid exists too so that gives tokens too. its grindy but it works
fortune boxes legendary are rare too not consistent but yes I've gotten legendary that way.