When Skylar had her feet sunk into the ground, Undyne was quick to prepare her energy spear. She launched spear after spear around the human's feet, circling her to ensure that she didn't accidentally stab her with a spear. That would not have been good, and Frisk would not have liked that, if they found them, of course. Shehad never encountered this monster before, but she was well aware that this wasn't going to be a battle to take lightly. even papyrus, the smiling doof that he was, must have figured out that these girl monsters were bad news.