<P> The character has been met with largely positive critical reception . </P> <P> Finn debuted at age 12 but has aged over the course of the show and is now 16 . Finn sets off on magical random quests around the Land of Ooo . He would gladly fight or beat up anything evil, but would not harm anything good or "neutral" as shown in "The Enchiridion!" when he refused to squash an innocent ant . Having a strong moral code, Finn swore that he would help anyone in need and often performs heroic feats to save the day; however, starting after season 3, Finn's enthusiastic nature becomes more toned down as the series progresses, suggesting he is both maturing and developing as a character as he ages . As shown in "Memories of Boom Boom Mountain", Finn appears to have been abandoned in the woods during infancy . He reveals that he had made "boom boom"--a euphemism for defecation--on a large leaf, fallen on it, and lay there crying until Joshua and Margaret, Jake's parents, rescued him from the wilderness and took him in to raise him alongside Jake, who became like a brother to him . As such, Jake is also Finn's adoptive brother . In "Henchman", when Finn is asked about his parents, he says Jake told him that he came from a cabbage, in jest . In the episode "Susan Strong", Finn states that he knows nothing of his human parents or any other humans . He is one of the few characters in the series (along with Flame Princess) who ages regularly . According to the episode "The Vault", Finn has had a number of past lives . In "Red Starved" it is revealed that Finn is color blind, believing that an emerald was a ruby . </P> <P> In the Season 6 opener "Escape From the Citadel", Finn has lost half of his right arm, up to his elbow, from which a flower protruded . He later regains his arm, now as a prosthetic, in the episode "Breezy", only to lose it once more in the seventh series finale "Reboot" when his grass arm transforms itself into a humanoid, sentient being . In the Season 8 premiere episode "Two Swords", Finn gets fitted with a new robotic arm by Princess Bubblegum, to replace the missing arm . </P> <P> Finn is currently 16 as confirmed in the season 6 finale "The Comet" and the early season 8 episode "Wheels". At the beginning of the series, Finn was a 12 - year - old boy who is supposedly the only known human in the Land of Ooo . During the episode "Mystery Train", Finn turned 13; it has been stated that the episode first airing date (March 14) is Finn's birthday . After season 3 ended, Pendleton Ward stated in an interview that Finn was 14 . Finn was 15 years old in the second half of Season 5, according to Adam Muto . In the Season 6 finale, "The Comet", Finn reveals that he has reached 16 years of age . This means that unlike in many other cartoons where characters stay the same age or age through time skips, in Adventure Time time passes regularly . </P>

What episode of adventure time does finn lose his arm