I figure the best way to get the pure is from the black market. Well worth 70 gems. On first batch I settled for a Ninja (didn't go for Lava), without know that Ninja is useless pos. But on next batch I went all the way up to get Pure. Gave it a try at breeding with Terra, but got a lame Flamming Rock...Now put him up with Dark and see if get anything out of it (showing 12 hrs breeding time...so not very hopefull and good dragons cost more time than that, I think)
to get legendary dragon is pretty easy but to get the pure dragon is all depends on your luck.. They said the chances to get pure is 1:64? Maybe that fact is not valid anymore. It should be 1:1000, lols!
^don't waste your gems. to get legend you must used dragon is on special list, for now everyone say "rare hybrid" actually is wrong but whatever you say about that.
to get legend type you need a dragon is on special list. legend + legend is never produce legend if is different species, if is same species just used simple logic flame + flame = flame. is wind + wind = wind, it wont produce other species of legend type =P also breed same species it will decrease chance to get pure.