Summary
Boruto's deadly jutsu, the Uzuhiko Rasengan, is incredibly powerful but comes with significant weaknesses. Uzuhiko requires Boruto to be grounded and vulnerable, making it risky to perform. Despite its flaws, Uzuhiko's limitless potential cements it as one of the series' most powerful jutsu.
Boruto has been nothing but a real monster since his debut. Boruto: Two Blue TornadoesBut the true power of his deadliest jutsu, the Uzuhiko Rasengan, is far beyond what fans imagined. With Konoha under attack by two incredibly powerful villains, fans have seen just how much training and hard work Boruto has put in during his years away.
In chapter #12 of Boruto: Two Blue Vortex, Boruto confronts Hidari after rescuing Himawari from Jura and teleporting to Sarada's location and protecting her. As expected, Hidari is a tough opponent driven by the desire to consume Sarada.
With Sarada holding Hidari back and buying time for Boruto to use his ultimate, he charged in and Hidari hit with Uzuhiko's Rasengan, destroying him and blowing him into pieces.
Uzuhiko is a double-edged sword
Despite its great power, it still has its weaknesses.
The Uzuhiko Rasengan first appeared in chapter #2 during the fight against Code, and it was shown to be extremely dangerous considering how it used the chakra of a planet and how Code was instantly defeated. However, that wasn't the full extent of its power that was shown, as Boruto managed to keep Code from retreating to his hideout and followed him there. However, when confronted by Hidari, Boruto had every intention of killing, and so attacked him with an amplified Uzuhiko. Interestingly, Boruto said that he hadn't fully charged the Uzuhiko but had no choice but to attack Hidari with it, meaning it can be much stronger.
Unfortunately, Uzuhiko has two potentially fatal weaknesses. Since Uzuhiko operates by collecting chakra from the planet, Boruto's feet must be placed on the groundand he can't fly or jump around to dodge the attack, as that would interrupt the process. The second weakness is that it takes a while to activate Uzuhiko, and the more chakra you absorb from the ground, the stronger the technique becomes. This leaves Boruto completely exposed and gives his opponent an opportunity to attack him.
Despite these weaknesses, Boruto's claim that the Uzuhiko Ransengan's power is limitless is impressive, as it instantly puts the technique among the most powerful ever seen in the series. The fact that it was able to obliterate one of the Self-Aware Divine Trees, arguably the most powerful villains ever to appear, is proof that Boruto's claim is not an empty boast.
Boruto: Two Blue Tornadoes did a great job of introducing an extremely powerful technique with the Uzuhiko Rasengan, while also giving Boruto weaknesses to ensure he's always ready. This ability also forces him to rely on others, which gives other characters time to shine.