50% Maximum Power (怪物フリーザ Kaibutsu Furīza, lit. "The Monster Freeza") is the three hundred twelfth chapter of the Dragon Ball manga.
Frieza tells Goku that he is impressed with his strength, but that he is getting bored with their battle. He asks if Goku would like to work for him, saying that he would make a much better subordinate than Captain Ginyu. Goku refuses, and Frieza says that he must kill him. He says that even though Goku has held back some of his power, 50% of his maximum power will be enough. Goku is surprised at this, and says that Frieza is bluffing. As the two stare each other down, Krillin wonders what is happening, and Piccolo says that they are looking for the right moment to attack. When Gohan asks if Goku can win, Piccolo says that he is unsure due to their incredibly high power levels.
Frieza then charges at Goku, hitting him with an elbow to the face. Goku staggers but does not fall. Frieza trips Goku with his tail, then wraps it around his neck and elbows him in the stomach. Goku kicks at Frieza, but Frieza easily leaps away. Goku charges at Frieza, but Frieza quickly turns and kicks him in the face, sending him flying backwards. He says that he is impressed that Goku is still alive, but notes that he is beginning to run out of breath. Piccolo worriedly thinks that the difference between their power reserves is too great. On his planet, King Kai realizes that the outlook is bleak. Yamcha asks if Goku is wearing weighted clothing, but King Kai replies that he is not. Tien confidently states that Goku will win the fight, since he still has the Kaio-ken technique. However, King Kai dejectedly tells him that Goku is already using the Kaio-ken x10.