You can't make a good deck w/ All Nightmare? o-0. Jungo too? o-0x2.
Here's my Jungo deck, gets you at least to 1200, and you have 1 star flexibility in case you need to bring in SOA or Stop: X
If you're still can't do it, you might want to sell some of your clans and try new ones.
Here is a deck that will keep u safe from bans and will be good its mono Skeelz.
it's a great deck trust me now for nightmares here is a good ban safe deck.
Glorg (to Oshitsune if he is unbanned)
Askai or Ongh its preference I like Askai better but Ongh takes down Ulu Watu and Bangers
Buba or Greow/Scotty if u r worried about Soa
Odile/Jalil i like Jalil
Wendy/Mindy i like Wendy
For that deck naheema to Askai or Ongh. but Jungo are usually not 1300+ material with out sylth, and not 1400 with out both him and Ongh. But there are exceptions to this (the dude who set the record). Skeelz are a very good clan which can change depending on the abilities you choose. But if you have all of the Jungo, sell Kreen Cr in a few weeks, then buy a clan you like...even if it is Rescue :sigh:
You can try my deck if you've got all the Nightmares, I'm sitting at 1313 and it was a pretty easy trip.
Also, despite what everyone says, Glorg is not that useful in mono Nightmare in my opinion. Replace Oshitsune with Azgaroth next week and you'll be fine.