At first glance I wasn't sure about this deck, but the more I look at it, the more I love it! You have a really sweet
balance of early disruption and late game powerhouses.
Goblin Dark-Dwellers is too good to not use, and this is an excellent use of him.
My only suggestions are small ones, because I think the deck seems pretty dialed in.
Kolaghan's Command is still standard, and can be cast off Dark-Dwellers. Automatic 2-for-1 is a great deal, and thankfully the price is starting to drop on it. 1 or 2 of would be plenty, plus it gives a mainboard way to deal with
Hangarback Walker and
Hedron Archive.
Your two big dragons are great, but are susceptible to removal/counterspells. Maybe having a
Gaea's Revenge in the sideboard for removal/counter heavy decks could get around this.
I hope you found this helpful! Good Luck and Happy Hunting