Trixie, in her pursuit of ancient and powerful magicks, has found herself on an island chain just off the coast of Equestria searching for powers to win in another duel against Twilight. During her conquests in the island chain, she stumbles on a unique opportunity. She'll soon discover just how unique this really is.

Humanized ponies

Note: I haven't seen any of the fourth season yet, but I heard it has some history about the princesses and the Elements. This story ignores all of that since I haven't seen the 4th season. Tagging Alternate Universe just in case, though.

A Florian fleet has arrived over Equestria as a way to discourage Discordia's aggression. At first they seem to be more than a match for Discordia's new, mysterious weaponry, but soon a strange new force takes its foothold in the war. The Florians will need all their power to live up to their own purpose.

First one here

Second one here

Two young men arrive in Equestria to distance themselves from Discordia. After a misadventure in Ponyville, Florians are found and brought to Canterlot to be confronted by the princesses for their "invasion."

Very little Tron, not like last time.

I didn't draw the cover art.

Prequel here

When the powerhouse country Discordia begins improving its military, a sure sign of war, Equestrian Princess Luna goes on a diplomatic mission to a mysterious country on the opposite side of the planet. Rumors indicate that this country has power and technology beyond anything previously imagined by the Eastern Countries. Does this mysterious country even exist, and will they provide military aid against Discordia?

Has some Tron-like elements; humanized ponies

Sequel here