I'm mixing dragons with 2 elements for a long time, but each time I got the 2-element dragon. How it is possible to create a dragon with 3 elements? I'm level 19. Is it level-dependent?
yes lvl is dependent and it also depends on what device your playing on and on what lvl the breeding sanctuary is
I suggest you lvl up on of the parent dragons you're going to breed to lvl 15 and one could be at 10 or higher but one must be at lvl 15. that's how I got the apocalypse. and your sanctuary might breed differently if you play on facebook or on mobile and usually mobile gives the best results when bred directly
so mud/waterfall + war would give you a better chance of getting quake on mobile than on facebook which requires a lot of different elements and I usually never get the quake by breeding directly so mobile is better