I am near master league and im barely getting by need help and good monsters and tips
Well the best way is to type down dem 16 digits and get lots lf gems instantly but just hoarding your gems and wait for guaranteed legend festivals works too
16 didget?
“Buy gems with a credit card” is what @Z19Kiwi is trying to say.
Credit cards typically have 16 digits unless you’re a baller with an American Express, which has 15 digits 
If you want a serious answer, save up 50 games and wait until there is a guaranteed legend on first hatch. You could get up to 3 or 4 of you’re lucky
I don’t agree with the save gems and wait, for beginners. I think in the begin is much funnier and useful try to get any monster you can, in the single egg or 10 eggs packs (if you can the hatch 10 is always better). Because even the epic will be very useful in your team and you can advance much faster to start save gems later. If I remember properly I already have around 3 or 4 legend monsters in my team and was much farther in the game when I ran my first 10 in 1 pack.
I think you can try to evolve more your monsters and use the remain cost you have with an other monster, and I believe there are at least 2 more monsters “hidden” in the islands, but don’t remember which island…