Banished once again, Sombra had nothing but his thoughts to pass the time. Unlike previous defeats, he felt calm despite being blasted back to the void. Furthermore, his cognitive prowess seemed enhanced as if emerging from a fog bank. As his return to Equestria drew closer Sombra modifies his plan to reclaim his kingdom.
A few elements from the IDW MLP Comics are added to the story but nothing that requires you to read the comics.
Edit: This story takes place after Season 9.
Entry for the Season 10 Bingo Writing Contest (Prompt 99).
So... Is this going to be Season 3 Sombra or Season 9 Sombra?
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This takes place after season 9