Nightmare Plains is a location in Monster Girl Quest: Paradox
This short, but highly dangerous area is the only way to Succubus Village and Lady's Village. Gelatinous Cube Girl, Youki, and Tiger Girl are the monsters that you'll encounter here. If a traveler assumes they can pass though it simply because they can take on the monsters outside of the area, they're in for a wake up call.
Seed of Power
Seed of Agility