Planes Gates

Planes Gates are quite possibly the most complicated invention of magically integrated technology in all of Aither. They were made long ago, during the Age of Founding, long before The Divine Exodus by the god Rahsbar, the First Gnome, who experimented with creating an inorganic version of the Rift Trees that did not require very specific powers to access. He created them throughout the world, attempting to link them with each of the different planes of existence. This is why the creation of Planes Gates is near impossible after The Divine Exodus, as it is said that their creation requires a divine touch, or at least knowledge of the arcane and the script that cannot be achieved by a mortal.
Many civilisations founded cities around Planes Gates if they came from or have a close connection with a different realm. An example of this would be the Planes Gate connected to the Feywild in the elven city of Elendir, the capital of The Ithryl Woods. They are quite easily accessed as well, requiring a certain understanding of the arcane, or being enough of a conduit to the divine to allow for the 'divine touch' that had once been used to create the Planes Gates in the first place.
They are rarer now than before, and a Planes Gate had not yet been invented for every plane of existence. What makes them even rarer is that some have been destroyed, as is the case with the Gate in Thantheas, which was reduced to rubble to prevent Lolth, the Spider Queen from escaping to the Material Realm. The lack of divinity walking amongst mortals in the Material Realm also means that the divine conduits that are in the world, such as paladins and clerics, tend to be weaker, with gods having to more carefully pick and choose their champions, given how their connection has been severed.

Access & Availability

Planes Gates are well known throughout Aither, but each is heavily guarded, and only a select few are even capable of accessing them.

Complexity

The creation of Planes Gates cannot be comprehended by most mortals, and even those that can use them do not fully understand their inner workings. To this day, no mortal has successfully created a working Planes Gate, despite them being around for several millennia, as each took even a god centuries to finish.