Oroboros silently chomps down on her own tail, and that is the end of that.

There's nothing to say to the sheer brute stupidity of that motion. Oroboros is known for one thing and one thing only, and that's shoving her tail in her mouth so that there is no beginning and no end. The perfect prison - the limits of the world itself. Nothing born of this world can escape her grip.

A faint green light begins to emanate from within her.

Her horns begin to grow. Simple, smooth draconic horns begin to extend and fracture apart, like antlers or like branches. A crown of leaves begins to open atop her head, even as her claws extend and begin to burrow into the earth like roots. Still she stubbornly bites down upon her tail but all along her back flowers begin to bud and open and shockwaves of grass run down her spine. 

Still she does not speak, struggle, or remove her tail from her mouth. But it is becoming increasingly clear that the World Serpent has bit off more than she can chew.