Dragon Ball Z: The Tree of Might

The Tree of Might is a parasitic plant that drains life force from the planet it's rooted in. It sucks energy from the water, flora, fauna, and ultimately the Earth's core to grow rapidly. Once fully grown, it produces a single fruit that grants immense power to anyone who eats it. Turles planned to harvest this fruit to gain enough energy to conquer the universe.

The forest fire that opened the movie was caused by Turles' probe, hinting at his destructive influence before the Tree itself appears.

Turles is a Saiyan, the same warrior race as Goku. Both share the characteristic spiky black hair and similar physical build. Unlike Goku who was sent to Earth as a baby and raised as a human, Turles became a space pirate. The Saiyan race naturally produces warriors with similar appearances, though their paths diverged dramatically.

King Kai's warning about an approaching Saiyan hints at the danger posed by someone from Goku's own race.

Gohan's tail regrew because he is half-Saiyan. Unlike full-blooded Saiyans who lose their tails as they grow stronger, half-Saiyans can experience tail regrowth, especially under extreme circumstances or stress. The Tree of Might's energy surge triggered this regrowth, allowing Turles to exploit Gohan's Great Ape transformation.

Earlier in the movie, Gohan demonstrated unusual power during the forest fire scene, hinting at his latent Saiyan abilities.

Turles created an artificial moon by manipulating energy, then forced Gohan to gaze at it. The moon's reflection triggers the Great Ape transformation in any Saiyan with an intact tail. The massive, feral Gohan then attacked his own friends and family, forcing Goku to intervene.

Gohan's tail regrowing earlier in the battle set up this transformation, as Turles had been watching for exactly this opportunity.

When Gohan became a rampaging Great Ape, Icarus the small dragon intervened and calms Gohan down momentarily. Taking advantage of this window, Goku threw an energy disc (Destructo Disc) that precisely severed Gohan's tail, returning him to his normal form. This technique required incredible precision to avoid killing his son.

Icarus's earlier bond with Gohan during the forest scene established their connection, making his calming effect believable.

The Tree of Might had drained so much life energy from Earth that there was insufficient natural energy left to power the Spirit Bomb. The attack formed but was too weak to harm Turles, who easily deflected it. The tree's parasitic nature had essentially emptied the planet's life force reservoir.

Earlier scenes showed the Earth drying up, animals dying, and water vanishing, all visible signs that the planet was already depleted.

Goku cleverly redirected the Tree of Might's own stolen energy against it. He channeled the massive energy the tree had absorbed from the planet directly into a second Spirit Bomb. This made the attack exponentially more powerful than a normal Spirit Bomb, since it carried the tree's corrupted energy plus whatever residual life force remained.

The first failed Spirit Bomb visually showed energy flowing toward the tree instead of into the attack, hinting that the tree was drawing power from everywhere.

Turles recognized Gohan as a half-Saiyan with significant latent power. As a space pirate seeking to conquer planets, Turles saw potential value in recruiting strong warriors. He attempted to appeal to Gohan's Saiyan heritage, suggesting they could rule planets together, though Gohan rejected this offer outright.

Turles noted Gohan's power during the earlier confrontation, when Gohan impressed him with his abilities despite being a child.

Icarus, the small dragon Gohan befriended during the forest restoration scene, flew directly to the rampaging Great Ape Gohan. His presence calms Gohan enough to momentarily stop his destruction, providing the opening Goku needed to safely sever his tail. Without Icarus's intervention, Goku might have been forced to kill his son to stop the rampage.

The entire subplot of Gohan saving and naming Icarus during the camping trip was specifically set up to pay off during this crucial moment.

Piccolo jumped in to shield Gohan from Turles' killing blow during their one-on-one confrontation. As the sole protector of the young half-Saiyan at that moment, Piccolo chose to take the hit himself rather than let Gohan die. This act reflects Piccolo's development from rival to protective mentor figure.

Piccolo had been training Gohan throughout the movie, establishing their mentor-student bond that made this sacrifice emotionally logical.