Ever since I first read the comic about how Rarity turned into a full power nightmare version of her,it kinda reminds me that there are something in Equestria that could resist the power of rainbow.Since I saw Nightmare Rarity smashed that rainbow power from her former friends,when they are trying to free Rarity from her nightmares.It got me thinking that what if the nightmare forces are the opposite of elements of harmony?I think so,cause that they could give anypony their immense power,fear and hatred,showing them that is better than having love and friendship. Don't you guys think so too?

Nightmare Star

Nightmare Moon

Nightmare Mane 6

Nightmare Cadence

Nightmare Shimmers