|This article is about a/an location in Kamen Rider: Dragon Knight.|
The Advent Void is the alternate dimension where Kamen Riders are sent after losing too much energy in a battle and disintegrating, simply called "Getting Vented". It appears similar to an "astral plane" of sorts, and has no gravity, Eubulon instead being shown to invisibly propel himself while floating. It is used as an alternative to the principle that defeated Riders are either killed by an attack or dissolve in the Mirror World that was used in Dragon Knight's original Japanese counterpart, Kamen Rider Ryuki, and allows for such defeated characters to return, a key plot difference between the stories.
The Advent Void is described as the place that lies behind the mirrors in between Ventara and Earth. It was designed as a fail safe in case a Rider was badly injured: they would be Vented and brought to the Advent Void, resting inside a stasis pod to recover until Advent Master Eubulon could retrieve them. This allowed them to fight with less caution and not have to worry about being excessively hurt. However, Eubulon had the only means of directly accessing and returning from the Advent Void, his unique Advent Deck called the Void Key. After Eubulon and the Key disappeared following his fight with Xaviax, the Advent Void ended up trapping the Ventaran & Earth Riders rather than simply saving them, thus making the war a fight for survival. When Eubulon returned, he was able to free the Ventaran Riders and Kit as Xaviax was in the final step of his plan to abduct Earth's population. After Xaviax was destroyed, Eubulon freed the other Earth Riders and wiped their memories of being Riders.
- Len refers to the Advent Void as "the world between the Mirrors", implying that it's the empty white space that the Kamen Riders traverse to get to and from Ventara, but when Eubulon retrieves the original Ventaran Riders and Kit, the Advent Void is an electrified blue and purple space containing floating pods with the Vented Kamen Riders asleep inside them.