Part of what makes ELO fun is that it's constantly changing. If it wasn't, the nature of UR would mean that just a couple of decks and a particular playstyle would emerge as dominant, and that would be that.
Your deck isn't necessarily bad, but if you want to do well in ELO, go experiment with the new stuff.
As for Roots, they are still an amazing clan -- they just got rebalanced a bit. They gained many strong cards over the last year.
I'm wondering if my deck is legit against all these new cards.
lately all the new cards 7 power or more, even those who cost 100 clintz on the market only.
If you get the clintz you can change Kenny Cr to wardom and Methane to sargh.
Kenny can cause problems because he only has 6 power and nowadays that can be easaly beaten.
GHEIST has not changed so much but for Nightmare you should pick up Artus (a 2* DR) and Cutey (a 3* Kenny Cr).