Potara

When two individuals each place a Potara earring on opposite ears, they are drawn together by an irresistible magnetic force and merge into a single fused warrior. The resulting fusion combines the power, skills, and personalities of both participants into one being that far exceeds the sum of its parts.

The rules governing Potara fusion have been clarified and revised across different parts of the series. Old Kai originally stated that the fusion was permanent, which is why Goku hesitated before using them against Super Buu. However, Dragon Ball Super later established that permanent fusion only occurs when at least one of the participants is a Supreme Kai. When two mortals fuse, the effect lasts approximately one hour before the individuals separate. Extreme power consumption can shorten this duration, as demonstrated when Vegito's fusion ended prematurely during the battle against Fused Zamasu.

Wearing a Potara earring is also a prerequisite for using a Time Ring, linking these accessories to the Supreme Kais' ability to travel through time. This connection was exploited by Zamasu, who stole Gowasu's Potara and Time Ring to carry out his genocidal plans across multiple timelines.

The most famous Potara fusion is Vegito, the combination of Goku and Vegeta. Vegito first appeared during the Buu Saga when Old Kai gave Goku his Potara earrings as a last resort to defeat Super Buu, who had absorbed Gohan, Piccolo, Goten, and Trunks. Vegito's power was so overwhelming that he dominated Super Buu even after deliberately allowing himself to be absorbed in order to rescue the others.

Vegito returned in Dragon Ball Super during the "Future" Trunks Saga, this time achieved by Goku and Vegeta voluntarily donning the earrings to combat Fused Zamasu. However, the fusion wore off unexpectedly quickly due to the immense energy expenditure of fighting in Super Saiyan Blue.

Goku Black and Future Zamasu also used the Potara to create Fused Zamasu, combining Zamasu's immortal body with Goku Black's Saiyan power. Caulifla and Kale fused during the Tournament of Power to become Kefla, demonstrating the earrings' use among Universe 6 Saiyans. Old Kai himself was the product of an accidental Potara fusion with an Old Witch millions of years earlier, explaining his wrinkled appearance and magical abilities.