Being frozen in a glacier for a thousand years is a terrible experience. For starters if you are anything but a unicorn you are completely screwed, no ifs, ands, or buts about it. However the fate for a unicorn in that situation is not much better. One must have a considerable amount of power and have knowledge of very unique spells, to prevent aging, death from hunger, and death from the cold.
Sombra was one such unicorn, he had to focus all of his reserves of magic to keep him alive, but that was not the hard part. The hard part was staying sane. Day after day of staring into translucent ice, with only his own thoughts to keep him company, and with an ever present hunger that could neither be fulfilled, nor could kill him it was difficult to stay sane a month least alone a thousand years. It was inevitable that the once eloquent, intelligent, but brutal tyrant king Sombra decsended into madness in his icy prison. However, he was there so long that he fell in and out of insanity countless times during his imprisonment. It just so happened that when Sombra was finally free he had been in a bout of insanity, and was not much more than a feral beast.
After his second defeat by the Cadence, Sombra would have preferred his prison of ice, or even eternal torture. When the power of the crystal heart overwhelmed his body he felt every fiber of his body being ripped apart. It was the single most painful experience of his unnaturally long life, but it quickly faded along with all sensation. Darkness took him, and he strained out of thought and time. Stars weaved overhead, and everyday was as long as the lifetime of the earth. After three years of feeling nothing, and being alone with his thoughts, all Sombra wanted was to cease to be.
Then one day something happened, something he didn't quite understand, something that would change his life forever. He suddenly heard in the darkness a word that he did not say.
"Carrot?"