Written by long-time fic author John Biles, My(stara's) Little Ponies: Friendship is Adventuring transports Equestria wholesale into the Dungeons & Dragons world of Mystara, and it mixes in beautifully.The story is told from the viewpoint of one Samus Marcus and on occasion another member of the party, later on in the story, a typical adventurer with a penchant for Nice Hats based on a character commonly used in the author's own campaigns over the years. We start off with Marcus and friend Ivan almost getting killed along with the rest of their party over a waterfall in the Malpheggi swamp, but are saved by the Elements of Harmony, registered Adventuring group in the employ of Princess Celestia. Turns out that they are aiming for the same goal as Marcus and Ivan.There's just one small problem: Marcus used to be Eric of the Northlands, who had a history with Twilight that.... well, let's just say that if she learned who he was, she'd blow him up. And if she didn't Spike would gladly burn him alive, if her new friends didn't do the job for him.A deadly serious Soap Operagoes on from there.Can be read with commentary and reviews on Spacebattles here, or edited and corrected in pure text-form here, or in text form with better formatting here.
What's this? A treasure trove of Tropes without facing certain death via dungeon traps? AHAHAHAHAHAHAHA!!!!
Accidental Courtship: It seems like poor Eric/Marcus simply cannot stay in Equestria without somepony falling for him.
Always Chaotic Evil: Averted with the resident Entropy Immortal Luna, and Pinkie Pie, whose Element, Laughter, is an Entropy Artifact.
Amnesiac God: Turns out, Marcus was on the path to becoming an Immortal, long long ago, but his patron Immortal eventually lost interest and abandoned him.
"He is wanted for the theft of the Water Elves' Pearl, an affair with a Minrothadi ambassador, wearing an Augrist high priest's hat when unqualified to do so, stealing the harem of a Thyatian Ambassador, mocking the Thyatian Emperor, wearing the Sacred Hat of Valerias inappropriately, misleading youth, mocking the gods, failing to pay for 8 sandwiches, and 3 moving violations. Among other crimes."
But for Me, It Was Tuesday: Inverted as Marquetta/Marjorie complains that Marcus doesn't even remembering raiding her lair, and specifically invokes this trope by name.
Casual Danger Dialogue: When Marcus first meets Pinkie Pie, when he is the only thing keeping them plus Ivan from being washed downstream:
"Hello, ma'am," I said. "I hope you are a great swimmer because I fear my hands
are slipping and we are about to be swept towards that waterfall over there."
Doorstopper: In digital form! Each chapter is referred to as a "book" for a reason.
Enemy Mine: A big one in the climactic battle. The conflict between Marcus, Ivan and the Mane Six on the one side and Marquetta and the Elements of Power on the other has driven most of the story so far, but even that falls by the wayside once a gate to the Nightmare Dimension opens and the forces of Hell itself threaten to march through and start conquering the world.
Evil Knockoff: The Elements of Power. Notable for starting out firmly convinced that the Mane Six are their knockoffs instead of the other way around.
Evil Laugh/Laughing Mad: Marcus does this a lot in his narrative, always either when he finds some misfortune on an enemy amusing (or has been successfully tricked) or when he's nervous, though usually for that part he'll just as often scream internally.
Expy: While it's doubtful that the author intended him to be this way, it's hard for a reader to not draw parallels between Samus Marcus and Ciaphas Cain, HERO OF THE IMPERIUM!!!
First-Person Smartass: Given that we are privy to Marcus' thoughts, this showing up really shouldn't be surprising.
Furry Reminder: The ponies rely on their sense of smell more than their sight for identifying others, and they have herd instincts.
When Marcus is changed into a pony, his scent is different while in that form. Soarin' makes the comment that his brain is telling him that Marcus has to be someone else.
When Marcus freaks out due to his transformation causing his brain to get new signals it never had before, his panic is picked up by ponies around him who in turn become nervous themselves which then feedbacks right back into him. It takes Rarity with Fluttershy's help to get him calmed back down. Marcus remarks to the reader that he understands now how stampedes are started.
Interspecies Romance: Marcus accidentally got caught in one with Twilight in the backstory. He later gets involved in a more intentional one with Rarity, using polymorph candy to avoid the obvious problems.
Jerkass Gods: Mostly averted. Some of the Immortals mentioned in the story may well qualify, but those that are actually shown generally don't treat mortals too badly (as much as Celestia and Luna don't trust their mother Loki once they learn he's taken an interest in current events, he's shown as a trickster who may well be up to no good but doesn't engage in any actual villainy onscreen). Even Marquetta, who's been trying to kill Marcus for real all this time for stealing from her hoard — she's a dragon Immortal, after all — in the now-remote past, is shown to have her (slightly) softer side in the end.
Knights and Knaves: Pinkie busts one of these in White Plume Mountain by asking a question they don't know the answer to.
The Mind Is a Plaything of the Body: Whenever someone shapeshifts, they gain the instincts that would be associated with the new body. Some even tend to forget about their true form while shapeshifted, like Fluttershy