@Catpone Cerberus
Sombra looked at her deeply there and considered her question for a few silent moments. "I never found the ability to read into other's minds...Yet. So allow me, to show you why I hate them so much..." he seethed, his eyes seemed to look almost hypnotic as he locked his eyes to hers. For a second or two, she can feel things getting fuzzy as she felt a powerful dark influence take over mind. Within that influence was a flurry of emotions and pictures. Pictures that would begin to come clear.
Her vision of the present moment was now lost in a vast battlefield. What she saw, at the time, was a vast frozen battlefield as far as the eye can see. It was clear, from what she was being shown - this was from the point of view of Sombra in the distant past. To Sombra's sides, there were highly armed stallions wearing odd looking facial helmets that completely covered their heads. These soldiers were armed to the teeth. Evidently, Sombra was charging at an oncoming wall of soldiers wearing golden armor - much like the guards seen in Canterlot, but the designs were notably dated and different. This was a very, very long time ago.
The sounds of the battlefield were extremely loud. There was many shouts, screams, and explosions all around. In the vision, Una caught wind of a group of Sombra's soldiers being blown up in an explosion. The soldiers were valiantly doing their duty to the very end. All around the battlefield, soldiers from both sides of the field were engaged in brutal combat. There was many carcasses of dead soldiers from both sides sprawled about the battle field.
Sombra was charging towards a group of enemy soldiers who had a group of his own soldiers pinned down. His dark magic power summoned in large black crystals in the air which he speared through them. While as brutal as this attack was, there were two of Sombra's soldiers in the group that had been brutally mauled by the enemy. Even despite their helmets having been removed, the enemy soldiers had still been intent on wiping them out just like the rest of the army.
It was clear that this was quite a brutal battle. The sounds of it all, the desperate cries of death resounding throughout the hauntingly chilly battlefield were eerie. In the distance, the Empire could be seen with assorted flags flying on high towers - all relating to dark magic, crystals, or some combination of the two.
This scene here must have been shortly after the Equestrians begun their invasion, and this was Sombra's forces defending the Empire. Una couldn't do much else but let the visions play their course. Sombra was in complete control of what she was seeing here - despite however loud Una may get, in truth, she was just in a deep trance where she wasn't moving - while Sombra was in front of her, showing these visions through a spell.