Pseudo souls ｢擬似魂ギジコン, gijikon, lit. "fake souls"｣ are devices developed by Rimuru to be a vessel for the heart core and are based on the core mechanics of Sarion's homunculi. Rimuru used pseudo souls as the base to hold the chaos cores of Treyni and the rest of the dryas doll dryads. These devices have not been mass produced by Tempest yet, so Rimuru is the only known source for them. In the anime, they are depicted as yellow orbs.
By embedding pseudo souls into monsters generated through master cores ｢魔精核マスターコア, masutā koa, lit. "magic cores"｣, it is possible to create avatars ｢仮魔体アバター, abatā, lit. "temporary magic bodies"｣, temporary bodies that users can possess much like homunculi, with avatar cores ｢魔魂核アバターコア, abatā koa, lit. "magic soul cores"｣. The Dungeon Dominators are one example of this, while in Gaia's case, its avatar was the body it was reborn in.
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Dimension Leap ｢次元跳躍, jigen chōyaku, Yen Press: "Trans-Dimensional Leap"｣: Allows the user to freely locate and travel to a location, even if is in different Dimensions or Worlds, as long as there's a guide or connection to it.
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Parallel Existence: It allows the user to split their consciousness and give flesh to independent alter egos of themself, referred to as other bodies ｢別身体べつしんたい, betsu shintai｣.
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Parallel Reincarnation: It is a combination of Pseudo Souls, Parallel Existence, and Dimensional Leap—albeit a degraded version—but it holds immense potential. This ability allows the user to split their consciousness, creating an alter ego of themselves and sending it into the cycle of reincarnation or to a specific world of their choosing. The consciousness then grows into a new soul and develops its own ego while maintaining a connection to the original soul and body through their soul corridor.
This means the user can have numerous clones of themselves scattered throughout infinity. Each clone, while starting anew, possesses limitless potential in addition to the knowledge, wisdom, and experience of the original, giving them a solid and refined starting point. Furthermore, as long as a single one of these clones remains alive, the original soul and body can resurrect indefinitely without any backlash.
It's similar to a player controlling an avatar in an MMORPG. The user can either manually control it or set it to operate in auto mode.