It is impossible to get stones for abyss unless you just flat-out pay for abyss dragon
I included screenshot that shows you where you can collect stones for abyss dragon, which is nowhere.
There are some people that purchased an abyss dragon, I got a few stones from a contest while ago, but abyss dragon is not released in gold chest or anywhere.
You can't get enough stones from a contest, there is absolutely no way to get this dragon, unless you flat-out PURCHASED it.
I mean, you can even get stones for Anubis dragon? But abyss dragon is unobtainable, yet a contest is being run over the weekend using a hero that nobody can get?
This reveals the mindset of Gree.
This is the ultimate insult to anyone that has ever played this game when it was run by perblue.