The sprawling metropolis of Ponyville has become a den of crime and evil. In a desperate effort to save her city, Mayor Mare appoints a most unusual defender of the peace. On weekdays, Pinkamena Diane Pie works as a regular salespony at Sugarcube Corner. But on weekends, she dons her heroic outfit, and goes forth as Chicken Mare, the most fantastic crime fighter the world has ever seen. Pinkie Pie will not rest until all criminals have been crushed by one blow from her mighty hoof.

Malazan Book of the Fallen crossover.

The thousandth solstice approaches. As ponies prepare for the celebrations, ancient forces begin to stir. A veteran soldier works to prepare his soldiers for the future. A deadly assassin returns to the city, bent on avenging a past betrayal. The princess of the sun looks on, detached from the world of the common pony. But behind her glowing exterior lays a dark past, with a secret that may spell her downfall.

Both are outcasts from their homes. Both are lucky enough to have found new homes. A pair of sellswords make their way from the streets of Foaledo into the legends of Equestria.
Temper looks forwards to a humble life working his families forge, until he is forced to flee for his life. Tarsus contemplates the mysteries of pony emotions, even though such an act alienates her from her kind. If the two of them are to ever succeed in life, they will need to find one another and unite, to create a pair that will make history.

On Nightmare Night, the veil between the world of ponies and the world of the spirits is lifted. Ghosts are free to wander the land, searching for victims on which to prey. The Thieves Guild is visited by one such ghost, and soon find themselves in a fight for their lives.

Most Equestrians have a nice life. They wake up each morning to a beautiful sunrise, they go to a job that perfectly fits their interests, and they retire each night to a peaceful sleep. Do any of them ever wonder why their lives are so nice?
As far as Soot Streak is concerned, most ponies are better of not knowing.
After a colorful incident from his past, Soot was conscripted into Princess Luna's personal supernatural hit squad. Now, he serves Equestria from behind a veil, keeping ponies safe from all the troubles they never think about. For Soot, life is simply a question of what will kill him first; the monsters he fights without, his own comrades, or the monsters he fights within.

Fafhrd and the Gray Mouser, the most famous duo in the history of swords and sorcery, have travelled far and wide. They have faced thieves, demons, even gods. But now, they face their strangest destination: the land of Equestria.

The land of Equestria has faced many enemies in the past. But these enemies fell easily, swiftly crushed by the heroes of Equestria.
The Thieves Guild of Equestria is making no such mistakes.
Chronicled here are the tales of the legendary thieves who faced guards, dragons, wizards, and even the princesses themselves, all for the thrill of adventure and the jingle of coins.

When a mysterious man arrives in Ponyville, claiming to be from another dimension on an important quest, what can Twilight do? He claims he is there to help, but is he really? Twilight cannot deny that he wields powerful magic, but without a doubt, there is more to this mystery traveler than meets the eye...