Two brothers, born within darkness. But as one lingers within the shores of the dark sea and mingles with the light, the other descends into its darkest depths.

But both are mere pieces to an even larger puzzle...

Cover sauce: https://www.deviantart.com/skyeypony/art/Run-935690201

After defeating Tirek, Cozy Glow, and Queen Chrysalis with the help of her dear friends, Princess Twilight Sparkle is about to truly ascend to the throne and rule over Equestria in both Luna and Celestia's stead. Unfortunately, her ascension isn't what she was expecting, and a shocking revelation is made.

Foreknowledge of 'Ark: Survival Evolved' isn't entirely necessary, but it does help nonetheless.

Editor: Demondude.

The Main Six have just defeated The Storm King, thus saving Equestria. They then celebrate their latest achievement with their friends and loved ones. However, during said celebrations, an eldritch horror of unknown origins rips a hole into the very fabric of reality; using the moon as a doorway to another world.

[Story continues in Terraria: Hardmode.]

Warning: Comment section may contain spoilers.

Foreknowledge of "Terraria", isn't entirely necessary, but it does help nonetheless.