The Trinity of Vengeance

*Training Start!*

Sans was out of breath, normally that would be no surprise but he wasn't just walking across a room this time. He put his hands on his knee-caps and breathed heavily. They'd been training for days and he'd even dare to say they were good at it. All across the open field snow piled up and around the place. Sticks and dummies were scattered around from practice. Gaster!Sans acted as their instructor, trying valiantly to get them in some sort of fighting shape. "Error!Sans rarely works alone so if your going to fight him you'll need to be able to fight multiple people at once." He summoned a barrage of bone attacks. "Dodge this please." He flung them at the three of them. "You three need to stop fighting as individuals and start thinking like a team. A trio if you will." Papyrus helped sans up. "Hey, I'll have you know I'm in wonderful shape!" He grinned. Papyrus butted in, "Besides if this guy is just one Sans how hard could it be."
Gaster!Sans smiled, "You of all people should realize that underestimating your enemies will be fatal." Chara walked over sharpening a red knife. "He's right you know. Let's go over the move one more time. Papyrus you surround him with bones on the ground I'll fill the air will knives to stop him from jumping Sans you use your Gaster-Blaster to stop him from teleporting. Ready? Go!" Focusing on a dummy Papyrus made the ground around it erupt with bones as chara's red blades filled the air. Before the dummy could move, (Even though it couldn't) Sans blasted it with His Gaster-Blaster. Gaster!Sans smiled, "Just like that."