Elena released a little bit of her killing intent. But that was enough to freeze the Mismatched Piece party. In her previous attack Elena didn't completely destroy the undeads instead she just damaged them enough to send them to the undead space every necromancer had. She would not be able to summon those undead for some time but she didn't lose any of her precious soldiers.
Elena didn't release too much of her killing intent so the adventurers were stunned not for long. The first one to break out of his stunned state was the swordsman of the team. He looked like a 27-28 year old man.
After that he instantly attacked Elena. Elena didn't take out a sword to fight him. She dodged all the attacks with minimal movements. The swordsman definitely had quite a lot of experience but in front of Elena it was nothing.