DB Chapter 302
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
"Freeza's Third Form" (フリーザ第２の変身, Furīza Dai-Ni no Henshin; Literally meaning "Freeza's Second Transformation") is chapter 302 of the Dragon Ball manga.
Freeza says to pay attention, as his second transformation will begin now. He begins powering up, spikes shoot out of his back, and his head becomes elongated. Freeza apologizes for the delay, and suggests they begin the second round of their fight. Kuririn doesn't think he's changed much, but Vegeta yells at him that he's completely different from before. Gohan notices that all of the damage Piccolo inflicted is gone, too. Meanwhile, Goku also feels how much stronger Freeza's ki has gotten, and wonders if he could even win once he's completely healed.
Freeza thinks that Piccolo removing his equipment has only improved his speed and self-confidence. Then Freeza charges at Piccolo, so Piccolo flies up in the air from the side. Freeza flies after him, and Piccolo thinks that Freeza may have power, but he has the speed. But then Freeza gets ahead of Piccolo, ruining that theory. Freeza starts throwing some tiny superquick shots at Piccolo, first at the knee, then the head, then his chest, and finally just a whole bunch all over the place. Gohan flies off to help him, and Kuririn tries to follow suit, but Vegeta grabs Kuririn's arm and says it's pointless for him to go. Instead, Vegeta tells Kuririn to nearly kill him. Vegeta looks down at Dende and thinks that if he has one more recovery from the brink of death, he should become a Super Saiyan!