They didn't have to wait long to find out who their saviour was. "Your Highnesses," called out a stallion as he rushed towards them. A pony they had grown familiar with ever since he'd somewhat forcefully, but not without merit, inserted himself into their lives.
"Paper," Cadence called to him as he approached. Shining would have done the same had the air in his lungs not refused to leave them. "What are you doing here?" the alicorn continued, her voice hoarse and breathy.
"Playing my part, Ma'am." Paper Letters reached them and gave a quick but respectful bow. "I saw you were in grave danger and couldn't help myself. I do hope I was of use, and I apologise for going against my orders to not interfere."
Shining was, briefly and distantly given his overwhelming tiredness, quite confused by how a single pony could have thrown a piece of crystal that big that fast, not to mention how he had no idea where Paper had even found whatever it was he'd actually rammed into Sombra. But on the other hoof, the event in question had just saved his life and his wife's, so he would have chosen not to question it for the time even if he'd had the mental and physical energy to do so in the first place.
He stumbled forward, and he almost fell. Paper caught him, and held him up. "I'll lend a hoof, Sir," he said, helping Shining along and doing the same with Cadence. Together the three of them began to head towards the buildings housing the other guards, specifically the one with the doctors where Celestia also was. There they were, a bit later, quite relieved to know Twilight had managed to stop the blast from destroying the town.
A bit before that, and a fair distance away, the oversized chunk of crystal that had ran over Sombra came to a halt at the end of a trail of broken buildings. There lay a thick pool of shadows, and from it Sombra began to take his maimed shape anew. Something stopped him. Red lightning crackled around his fluid body, digging into his not yet flesh. He hissed and roared, and blindly charged forward in his incomplete state, his body little more than an unfinished head trailed by a snake-like tail of darkness.
He did not move much. Before he could reach farther than the area he'd covered as still a pool of shadows he painfully bounced against an invisible wall of force, and yet more energy burned into him. Red runes in a circle began to glow on the crystal ground around him, trapping him there no matter how hard and often he attempted to free himself by lunging against the invisible walls of his prison.
A voice spoke a short distance away, as a hoof touched the ground. "It ends here for you," it coldly whispered. The runes grew brighter, the crackles of energy within the circle grew more intense. Sombra screeched, and his voice twisted and distorted as his body began to fold in on itself. It lost all and any recognisable shape, consumed by the searing energy discharges inside the circle, it withered and bent and dried and screamed, and finally nothing was left of him but a few scorch marks on the crystal ground.