During the war to save Ace, Luffy uses Gear 3 briefly to break through the wall defenses created by the Marines. He uses "Gomu Gomu no Giant Stamp" to smash through the siege walls, showing that he can now use the form more fluidly, though he still shrinks afterward (at this point in the story).

) without shrinking. One Piece Wiki +3 Major Battle Moments Opponent Arc Key Attack Rob Lucci Enies Lobby Gigant Pistol, Gigant Axe, Gigant Whip Gecko Moria Thriller Bark Gigant Jet Shell (combined with Gear 2) Magellan Impel Down Gigant Stamp Sengoku Marineford Gigant Fusen (to protect Ace) Kraken/Hody Fishman Island Elephant Gun, Elephant Gatling Kaido Wano Red Roc (combined with Gear 2 and Haki) For more details on these techniques, you can explore the One Piece Wiki’s Gear 3 page or the Crunchyroll guide to Luffy's Gears . Would you like a breakdown of the

: Initially, after using Gear 3, Luffy would shrink into a miniature version of himself for a period of time equal to the time he spent in the form, leaving him vulnerable.

: After his two-year training, Luffy mastered the form, allowing him to use it without shrinking. He also began combining it with Armament Haki for attacks like Gum-Gum Elephant Gun . One Piece: All of Luffy's Gears, Explained - Crunchyroll

Monkey D. Luffy first uses (Gear Third) during the Enies Lobby Arc in Episode 288 of the anime and Chapter 403 of the manga .