Every Nightmare Night, Arsennas species becomes a race of insatiable tentacle beasts, hungry for sustenance.

During this, her body changes a bit. The fluid she secretes turns from cloudy white to black, as well as her blood. The fluid begins seeping through the layer of skin, causing black streaks all over the body, and darkening it as a whole.

In addition, she no longer has the ability, nor the desire to keep her complete disguise as a pony, and as such, there will be gaps in the skin coating, exposing the tentacle structure underneath.

This creature will stop at nothing to get what it wants.