It's impossible to not get a legendary after opening 40 pack without any. You probably got your's in the first 10 pack since you have to open a legendary in the first 10 pack at the beggining of an expansion. So, if you oppened your first legendary after 10 packs (the maximum possible) 42-10= 8. you should get a legendary in the next 8 pack (worst possible scenario).
This time i opened 150 and got 5 legendaries... Pretty bad result... but then in Kobolds I got 7 from 100... you win some... you lose some... it sucks but opening packs is all about RNG. Next time you could be the one opening 1 every 10 packs!
You're a fuckin asshole bud. 42 packs is a lot of money if you paid for them, and getting 1 legendary kind of ruins your whole experience for the expansion. The rewards system is clearly broken here, and maybe you could be a little more sympathetic to someone trying to have fun playing the exact same game you are. People like you make me sick.