I think that breeding 2 black dragons such as night and lotus gives you the highest chance of a night dragon.
Really fed up about the black gems. I have bred and sold loads of night fails recently. If I didn't like the design of these dragons so much I would just not bother with this event.
I do not like the way these tales events are going. Too much reliance on luck in terms of breeding certain dragons. Hard work and effort should be rewarded. Not luck!!!