On activation, a "Neat!" or "Nope" prompt will appear, similar to the one prompt that appears from activating Maxwell's Door.
Upon opening the chest, the player must battle a Shadow Maxwell who is equipped with his own Dark Sword and a special Telelocator Staff, with the ability to summon high-damage explosive meteors which can easily kill the player in one hit, should they go about unarmored. The landing point for each meteor is telegraphed by their shadow.
Upon defeating waves of Shadow Maxwells, the portal will reactivate, and interacting with it will bring the player back to their current world, with all items intact. If the player sticks around after beating the arena, they can activate the special shadow Phonograph that will spawn. It will play Morse code when turned on, that when translated, says "exordium". Entering the password to will redirect the player to .
- There is a broken bridge leading to a large island, unreachable without cheats. On this island are a few plants that can be typically found in the Grassland biomes.
- An easy way to reach the island is to use a Telelocator Staff using c_give ("telestaff") on the console.
- The crafting quote for the Shadow Portal ("Oh, the places you'll see.") is a reference to Oh, the Places You'll Go!, a book by Dr. Seuss.
- The author listed for the mod is Mr. Skitts.