The Nightmare Creature

Magnus, you are knocked backwards off of your feet next to your friends. Both of you take 18 points of damage as he shouts the wall of blades just kind of explodes outwards. John is surrounded by these tendrils of darkness emerging from his body encircling him and the sword in his chest. And soon he is simply a swirling column of darkness standing 15 feet tall with skeletal wings made of multicolored light. It's emerging from a black opal pool where it's buried up to its thick jagged torso.