"The Demon Realm has amplified its effects. Whoever eats of the fruit of the Tree of Might will gain incredible power beyond compare."
It is Fruit of the Tree of Might that has been exposed to the Demon Realm, greatly amplifying its effects.
The Fruit causes the consumer to acquire the Villainous Mode power-up, causing them to produce a dark aura and their eyes to glow red.
After consuming the fruit, Turles and Slug notice that their bodies begin to swell with Dark energy, which causes Turles to surmise that Towa tainted the fruit somehow. Eventually Towa reveals that she modified the Fruit in order to test out a new spell that sacrifices life force to achieve greater levels of power. This results in Turles and Slug transforming into an unfinished version of the Supervillain form by shaving off some of Turles and Slug's life force. Despite the power Turles and Slug gain, they are ultimately overpowered and defeated by the Future Warrior and Trunks: Xeno.
At the behest of Turles, Towa uses her knowledge to grow some Fruit of the Tree of Might to assist Turles and Slug in altering history for the Time Breakers. Towa amplifies it by exposing it to the environment of the Demon Realm, causing the Fruit to occasionally emanate an aura of dark energy. According to Towa, whoever eats this Fruit will gain incredible power beyond compare.
Towa, Mira, and the Masked Saiyan eventually manage to track down Turles and Slug in order to supply them with the Fruit. After Mira admonishes Lord Slug for acting on his own, Turles inquires about the Fruit and Towa gives some of it to him and Slug.
During the Battle on Planet Namek in Age 762, Turles gives Burter and Jeice some of this Fruit causing them to power up and gain the Villainous Mode power up. Upon seeing it, Old Kai identifies it as the Fruit of the Tree of Might, divine fruit that is intended only to be consumed by the deities such as himself and Chronoa (conforming to the Tree of Might's original depiction as Fruit of the Gods), however he is unaware that it had been modified by exposure to the Demon Realm.
Turles and Slug later use the Demon Realm-enhanced fruit to power up in order to deal with the Future Warrior. After consuming it Lord Slug reveals to the Future Warrior (and their allies observing the battle from the Time Nest) that it had been enhanced by the effects of the Demon Realm.
Though their power increases exponentially, Turles discovers that Towa had tainted the Fruit causing himself and Slug to swell with Dark energy. Towa and Mira later appear and Towa reveals she decided to try out a new spell that sacrifices life to increase power and decides to use Turles and Slug as test subjects, causing them to take on an unfinished version of the Supervillain form. However, despite the power of their new form, they are overpowered and defeated by a combined Energy Wave and Burning Attack from the Future Warrior and Future Trunks.
Outside of the main story, the Demon Realm version appears in Parallel Quest 19: Ginyu and the Fruit where Turles will appear and give some to the Ginyu Force. Captain Ginyu even compares its effects to being equal to him stealing a "perfect body". If the quest's Ultimate Finish achievements are met, then Turles will fly off to the Wasteland and give some of the Fruit to Vegeta. Turles will also eat some himself, leading to a battle with both Dark Vegeta and Dark Turles.