Upon performing the Edge of the Hidden Realm ritual, you will find yourself looking at an Inversion Pillar. Right click this pillar to be transported to the Antechamber, your first foray into the Demon Realm.
There are a few things of note in this first room:
• A single treasure chest containing some basic loot and, if you are lucky, a few Iron Keys.
• Secondly, a number of Doorways, each locked with a Dungeon Seal. Use a Key on these seals to unlock the next room.
• Thirdly, an Inversion Pillar, a mirror of the one you summoned previously. [ПКМ] this to return to your world.
There's also a large number of decorative blocks here, should you feel your home base needs some pizazz.
Any additional rooms you open from this antechamber will contain some combination of loot, monsters, traps and possibly some unactivated rituals. Keep your eyes peeled!
A few examples of loot that you might find:
• Enchanted Books
• Enchanted Weapons and Armour
• Various Anointments
• Demon Will
• Potion Ingredients
• Tau Fruit
• Saturated Tau
• Tau Oil
So get hunting and keep an eye out for treasure and traps alike!