Harmony Versus Dissension

Based on my fanfic I’m currently working on. When a mysterious pony arrives in Equestria, he gathers villains from the past to fight Twilight and her friends. The mysterious pony, Nightmist, promises his group wealth and power if they were to eliminate the mane six. Will Twilight and her friends be able to fight Nightmist’s group, “Dissension?” Who is Nightmist and what is his grudge against the wielders of the Elements of Harmony?
Note: Many people asked me some questions so I guess I'll just answer the commonly asked ones on here.
Q: Where is Discord?
A: He is in the story, but he isn't part of the team. Plus he is a god like figure. He would stick out.

Q: Wouldn't Queen Chrysalis and her Changeling army wipe everyone out?
A: She will not have her army. Why? Stay tuned and find out why.

Mane 6 vectored by
Trixie vectored by
Gilda vectored by
Flim vectored by
Flam vectored by
Queen Chrysalis vectored by
Rover done by me as you can tell how badly his ears were done.
I forgot where I got the background, so credits to whoever did that.
My Little Pony: Friendship is Magic is owned by Lauren Faust and Hasrbo