I'm entering my bad guy into the running.
Most of Snow's attacks are icy in nature. His bone attacks are encrusted with ice, and his Gaster Blasters' beams make ice spikes erupt from whatever they hit. He can fling his opponents around with icy blue magic, and also lock them in place with mint green magic. He has zero compassion and thinks he's above everyone else. He even has the guts to sass Nightmare. He just has a very cold aura and can frost over anything he touches if he so chooses. To keep from freezing solid, he wears heavy clothing and smokes. (I do not encourage smoking.) If pushed to the brink, he will cast the forbidden Snowgrave spell with zero remorse. Be very careful to not tick him off. However, like anything frozen, he is very brittle. He can't dodge as fast as Classic Sans but is very good at blocking.
Nightmare sent Snow to a strange new AU to increase the already-abundant negativity. And Snow knew exactly what to do. While Autumn and the others are distracted with each other...
He's supposed to be scratching his bone dagger across a white picket fence and frosting everything if it wasn't clear. All these light colors are hurting my eyes, I already regret this 
