Junkrat and Roadhog break into Winston's lab at Watchpoint: Gibraltar to steal some technology. Instead of winding up with loot, they wind up in Equestria.
With the Enchantress no more, and The Tower of Fate destroyed, The Order of no Quarter members decide to scour the remains of the tower for resources, but find a portal which transports them to a land of colorful ponies. Shovel Knight crossover.