It takes Ruka a long moment to pin the face of this troll. His face looks so different painted with fear than it did when he first arrived, and the colors of blood are distracting, but finally the information comes to her. This is Karkat, she remembers, just as he turns his back on her. Her attention shifts when his does, to the sudden party of dead trolls (with a handful of humans mixed in). She recognizes a few -- her attention, of course, immediate locks on the Eridan in the group, stitched up and injured and empty-eyed like the rest.

But it's more than a dozen to one, he doesn't look like he's fairing well at all. To be honest, it looks like he's going to lose, and violently.

Ruka focuses on the burning scars of her right arm, willing that power to her command; it and the bubble around her glow a brighter red, and its translucent surface begins to expand.

The wall touches Karkat, and then passes through him as easily as water through air. Once he's within its boundary, however, its strength returns. When one of the trolls rushes to make a forward slash at Karkat, they can only scrape across its surface. It does no damage; the wall of the bubble doesn't yield for a moment.

It dampens sound and sensation both of what lays outside its diameter, protecting in every way it can the two kids barricaded inside.