Artifacts are known to be special items that grant various abilities to those who possess them. They exist in the very fabric of time and space and have been known to exist in every timeline. If one artifact is to be destroyed, then the the same artifact in every other timeline would be destroyed as well.
The main plot of the Xenon story arc describes the active hunt that makes up the game's story. The Alliance, a mafia firm consisting of teams Dimensionia and Varia, are attempting to salvage all eight and lend their power to the teams' members. However, after Gardi Nakara, Jay Lucero, and his interns are picked up, Gardi reveals that at this point, Xenon Karambit betrayed the Alliance by making a deal with Trumpet Gang member Robot Moe. He attempted to collect the eight before the Alliance acquires them first, and use them for domination. However, he was defeated by the Alliance before he could set this plan in motion, with his ultimate fate unclear.
The Keido Arc features a new, growing Dane Gang on a "bizarre adventure" to stop the Cartel, a group of interest who damaged the timeline with the sixth artifact and trapped nearly all of the Alliance who were still on Earth (Dimensionia was in their ten-year training during this period.)
This list contains all of the current known artifacts and their abilities, and who owns them.
Note: Only 6/8 of the artifacts are known as of now. Others will be revealed at a later date.
Phantom Mask/King's Mask
The Phantom Mask refers to two artifacts: the KING Mask, and the Phantom Mask. After defeating Robot KING, Cielo acquires the KING mask, which is the first half of the complete mask.
Kidd later explains that equipping it will greatly enhance Cielo's power. Cielo then puts on the mask, having greater attack power but suffering from a side effect of slower speed.
The Phantom Mask is the other half of the mask, and is being chased after by Moe and Xenon. both failed to take the mask, as Ineur has it and was seen wearing it in Act 31, where it fought the alliance with Gladia.
Fused together, the complete mask is one of the strongest known sources of power. It also appears to generate purple sparks as seen on the mural describing the mask.
Bloxy ColaBloxy Cola is Cielo's main weapon of choice. It is said to be the second most strongest artifact as explained by Kidd. It is not yet known what the Cola does or if it's even a real artifact for that case.
Characters who possess this artifact include: Cielo/Phantom Mask Cielo
20-Sided Die / D20
The 20-Sided Die is Inechi's main weapon of choice, granting the user the ability to bind creatures into attacking fighting for her.
Characters who possess this artifact include: Inechi, and possibly Rhinechi, although he possesses a significantly weaker version.
Solaris' artifact is an item that has no weapon use, but can be used to track anyone who is within the sun's reach. In the case of Xenon, it functions like a scanner radar, since he can disappear from the sun's reach at his own will.
Nick Nebula originally had this artifact, before giving it to Drakon and Team Varia.
The sixth unnamed artifact provides a devastating effect on time. Its only known function is to trap people in a timelock, preventing them from aging or progressing forward in time.
The Cartel collectively owns this artifact and used it to seal everyone except for Team Dimensionia and the Dane Gang (this is due to the fact that both groups were non-combatant with the Cartel at the time.) There are other potential allies unaffected, but as of now the only two known individuals that fall under this group are Nick and Keith.
Currently, there is no way to reverse this timelock effect according to Nick when he said it to the Dane Gang. (Which is partially why Nick needs to gather up people quickly, starting by bringing together the eleven members of the final Dane Gang.)