Mazoku Enjin

Mazoku Enjin (魔族円陣, Demonic Rings), sometimes known as the Hollow Rings (虚リング, Horō Ringu), is a set of 6 rings that encompass certain hollow abilities. Each ring takes a different appearance from another. The current users are unknown as of yet.

Overview
The Mazoku Enjin, known to only a few people, has the ability to encompass certain Arrancar abilities - the most common being that of Cero and Bala. While it usually can only take a single ability, some of the more powerful users might be able to add in a second ability, though the primary ability would be relatively more powerful then the second. Some have discovered that the rings' were actually created from different Hollow Masks. Therefore, the powers for each ring fluctuates. Despite it already being made from Hollow Masks, the reiatsu contained is not enough, causing the user to have the need to absorb more Hollow reiatsu into the ring.

While the appearance usually stays the same, an extremely powerful user is able to change it's appearance to either hide the true form, or just to "fit their clothes". However, after it gains more and more reiatsu, it will be harder to change it's appearance. The creator of these amazing rings have yet to be found.

Activation
Aside from needing to have reiatsu absorbed into it, there isn't much of a specific way to "activate" the rings. However, the more reiatsu it absorbs, the more powerful the ability or abilities become. Due to that condition, actual Arrancar seem to not only not fit well with the rings, but also reject the ownership due to the need of killing their own type of people. However, it is still possible for an Arrancar to use it. The most common users of the Mazoku Enjin are the Quincy and the Shinigami.

Every ring has a "soul", similarly to a Zanpakutō. A user, if they have been "associated" with the ring for a long time, is able to speak to this soul. However, this "soul" is different for each user. As such, when the ownership is changed, all the reiatsu collected will also reset, causing the new user to have to collect the reiatsu again. Also, if the "soul" of the ring dislikes the user, it will reject the user of its powers, showing that the ring actually chooses the user, and not the other way round.

It has been found out by Shitoki Arata that each of the rings actually have a deeper power. In order to access that, one must be not only be strong enough physically, but also mentally. Due to that, one has to concentrate so well that even a lion's roar can't break their concentration.

Powers & Abilities
Every ring has a different ability as mentioned. Some rings can retain a second ability after it gets changed, though it isn't common. Due to each ring having a different appearance, these are only some of the basic powers.
 * Enhanced Strength: In addition to their usual strength, having one of the Mazoku Enjin grants a bigger amount of strength to the holder. This extra strength, also shown in each soul of the rings, has provided an even better chance of defending against extremely strong arrancar.
 * Reiatsu Absorption: Due to needing Hollow reiatsu to work, the ring itself grants the user to be able to absorb reiatsu into the ring, in order to make it stronger. This can only absorb reiatsu from Hollows, Arrancar and Vizard. If it absorbs any other types of reiatsu, it will eventually break it's ownership and move on to another.
 * Enhanced Speed: Probably due to it's base in Sonido, a bearer of the ring's speed would increase. A shinigami who was unable to use Shunpo before, for example, can be as fast as a normal seated officer's shunpo.

Rings & Owners
This is a list of rings and their owners.