No . overall No. in season Title Supervising direction by Written and storyboarded by Original air date Prod . code U.S. viewers ( millions ) 267 `` The Wild Hunt '' Cole Sanchez Sam Alden , Erik Fountain & Polly Guo September 17 , 2017 ( 2017 - 09 - 17 ) 1054 - 275 0.77 Still feeling guilty over Fern 's death , Princess Bubblegum tasks Finn to protect the banana guard from a monster later dubbed `` the Grumbo '' . Finn ca n't bring himself to slay the monster as he keeps seeing Fern 's face materialize when he 's close to defeating it . Later , Finn meets up with Huntress Wizard ( voiced by Jenny Slate ) who is also trying to slay the Grumbo and she tries to give encouraging words to Finn . They find the Grumbo 's cave and Finn once again stalls . Huntress Wizard puts herself in harm 's way and Finn imagines Fern in her place and finally slays the Grumbo . Afterwards , Finn and Huntress Wizard casually admit their feelings for each other and realize that the Grumbo was artificially created . Uncle Gumbald plots to create another monster using the remains of Fern . 268 `` Always BMO Closing '' Diana Lafyatis Graham Falk & Kent Osborne September 17 , 2017 ( 2017 - 09 - 17 ) 1054 - 273 0.77 BMO and Ice King become door - to - door salesmen by posing as one body ( Ice King as the body and BMO as the head ) . After selling a stick to Tree Trunks , the two get lost and end up at the dungeon where Gumbald is staying . They sell him Finn 's baby teeth which he happily pays for with a silver cup . Finn is outraged that his baby teeth were sold and is further mortified when Baby Finns made of teeth begin attacking the tree house . Through Ice King 's encouragement , BMO `` sells '' two mallets to Finn and Jake and they successfully defeat the teeth babies . Afterwards , Gumbald admits that his current plan was a bad idea . 269 `` Son of Rap Bear '' Diana Lafyatis Seo Kim & Somvilay Xayaphone September 17 , 2017 ( 2017 - 09 - 17 ) 1054 - 276 0.77 While at a party , Flame Princess accidentally signs a contract from Toronto stating that if she loses in a rap battle against Son of Rap Bear ( voiced by Dumbfoundead ) her kingdom will be forfeited to Toronto . She and Finn go meet Rap Bear ( voiced by Rekstizzy ) who explains that his son literally blew his legs off , frightening them . Despite training , Flame Princess still feels ill - prepared , and so she visits her father , the deposed Flame King ( voiced by Keith David ) . She attempts to mend their rocky relationship , but much to her frustration , her father seems oblivious to the pain that he caused his daughter . Later , at the rap battle , Flame Princess begins to lose her composure , but after seeing the still - unapologetic Flame King in the crowd , she angrily expresses her frustrations with her father in a rap . The track impresses the crowd , and Flame Princess defeats Son of Rap Bear . 270 `` Bonnibel Bubblegum '' Diana Lafyatis Hanna K. Nyström & Aleks Sennwald September 17 , 2017 ( 2017 - 09 - 17 ) 1054 - 274 0.77 When Finn presents the silver cup from `` Always BMO Closing '' , Princess Bubblegum decides to tell him , Marceline and Jake some more of her history . 800 years ago , a child version of Bonnibel discovers a family photo and decides to create a gum family . She creates Uncle Gumbald , Aunt Lolly and Cousin Chicle to help farm the area . However , her family quickly turn on her with the prospect of `` branding '' their family . Gumbald creates a juice that transforms those into low minded candy people . Bonnibel fights back , transforming them into her eventual candy civilians and deciding on the title of princess . In the present , BMO reveals where it got the cup . 271 5 `` Seventeen '' Cole Sanchez Seo Kim & Somvilay Xayaphone December 17 , 2017 1054 - 281 0.76 At Finn 's seventeenth birthday party , held at the Candy Kingdom , Princess Bubblegum , Marceline , Huntress Wizard and BMO present Finn with gifts . Suddenly , the Green Knight ( voiced by Brad Neely ) arrives and presents Finn with his own gift , an ax that he will reward him with if he attacks him with it . Thinking this is one of Jake 's tricks , Finn beheads the Green Knight only for Jake to arrive and the Knight challenges him to a battle by blocking him from his friends . Finn accepts and the two play 2 / 3 with the party games held at the castle . While arm wrestling , the Knight reveals himself to be a revived Fern who makes short work of Finn . He is stopped by Gumbald , Lolly and Chicle who were returned to their original form by Lumpy Space Princess transforming Ooo at the end of Elements . The trio and Fern leave as Finn is devastated by his loss . 272 6 `` Ring of Fire '' Cole Sanchez Tom Herpich & Steve Wolfhard December 17 , 2017 1054 - 277 0.76 Tree Trunks gets a call from her old flame Randy ( voiced by David Herman ) who wants his old ring back to propose to his new girlfriend . In flashback , Randy proposed to Tree Trunks after graduating high school . Immediately afterwards , Tree Trunks left him and became a pirate on the sea where she met and married Danny ( voiced by Raza Jaffrey ) . She breaks up with him due to him lying to her and she moves on to becoming a CEO to a shipping company . She marries her employee Wyatt , but due to his clinging attitude breaks up with him and he flees with the ring . Mr. Pig , who followed arrives as does Wyatt who still has the ring . Randy gets it back and Tree Trunks and Mr. Pig reaffirm their love . 273 7 `` Marcy & Hunson '' Cole Sanchez Graham Falk & Adam Muto December 17 , 2017 1054 - 278 0.76 Peppermint Butler gives Finn a new sword , the Night Blade . However , he also summons Hunson Abadeer . Peppermint Butler allows Hunson to roam the earth for one day and is restrained from using his powers . Finn and Jake take him to Marceline who is once again annoyed at her father 's ignorance . When Finn and Jake let slip that Marceline has a solo concert for ghosts , Hunson forces his way in . Marceline gives her performance , but it is interrupted by Hunson 's interference . Chicle , who has been following them , instigates a ruckus with the ghosts who proceed to beat up a weakened Hunson . Marceline is also powerless from stopping them , but Finn 's new sword saves them . The group escape and meet with Princess Bubblegum and Marceline and Hunson make up . 274 8 `` The First Investigation '' Diana Lafyatis Hanna K. Nyström & Aleks Sennwald December 17 , 2017 1054 - 279 0.76 Kim Kil Whan sends Finn and Jake to Joshua and Margaret 's old office after one of his employees get frightened by something . Finn and Jake witness strange ghosts and other sightings as objects move around . Finn suddenly sees baby versions of himself , Jake and Jermaine and gives Jake a wet willy ( earlier Jake claimed that Finn had given him one years ago and he denied it ) . Realizing that the ghosts are time remnants , Finn tries to look for the source while Jake accidentally scares Kim 's employee and sees his own birth from `` Joshua and Margaret Investigations '' . They discover that one of Dr. Gross ' experiments , Time Bear , had been behind it and fix him with Finn leaving a note for past Joshua and Margaret . While outside , Jake meets his alien parent , is turned blue and taken away leaving a note for Finn that reads `` BRB - Jake '' . 275 9 `` Blenanas '' Diana Lafyatis Sam Alden & Patrick McHale March 18 , 2018 TBA 0.53 Bummed about Jake being gone , Finn reads an issue of Ble Magazine and comes across a doodle of a caveman with his leg getting bit by a dog while a psychiatrist sits next to him . Finn writes `` Ouch ! Hey this is n't helping at all ! '' . He shows it to BMO and Princess Bubblegum , but neither get it . Finn shows it to Ice King who reveals that he wrote to Ble Magazine to have his stories published , but they never were . They find the building guarded by a passive pudding troll and discover that the building has been abandoned for years . They decide to publish a new issue with the joke , but the pudding troll does not get it either . Finn comes to terms with the possibility that he just is not funny , but upon returning home he slips on some banana peels , rips his pants and crashes into a message chair . BMO and NEPTR laugh as Finn smiles . 276 10 `` Jake the Starchild '' Cole Sanchez Hanna K. Nyström & Aleks Sennwald March 18 , 2018 TBA 0.53 Immediately after `` The First Investigation '' , Jake is taken by his dying alien parent , Warren Ampersand , to his home planet and discovers he that must defeat an evil alien to save the inhabitants . Warren gives Jake a special belt while he wears one himself . As Jake uses his stretching powers , he becomes weaker and Warren becomes younger , revealing that the belts drain Jake 's youth and energy . When Warren reveals his scheme as well as the fact the planet and evil alien are not real , Jake switches the belts and tricks Warren into giving his powers and youth back . Warren then tries to escape back to Earth after learning that Jake has children he could siphon from , but Jake tosses him into a black hole , leaving him stranded on the now empty space rock . 277 11 `` Temple of Mars '' Diana Lafyatis Tom Herpich & Steve Wolfhard March 18 , 2018 TBA 0.53 Finn is visited by Jermaine who reveals that Jake is in space and that they must rescue him . They head to Mars where Normal Man , now King Man , has Betty doing labor to `` cure '' her . King Man has them enter a cave to search for a device to save Jake and encounter various puzzles . Eventually , they come across Past Betty who was to go on a trip in a week , but met Simon changing her plans . Finn and Jermaine tell her that Betty needs to think about herself and she `` changes '' her past so that she left that day instead of in a week . The cave turns out to be the device and they are reunited with Jake . However , Betty tells King Man that seeing Finn retrieve Jake has only increased her interest in rescuing Simon ; she declares that she now has a plan to not only save Simon , but also retrieve Margles from GOLB , which frightens King Man . 278 12 `` Gumbaldia '' Diana Lafyatis Sam Alden & Graham Falk March 18 , 2018 TBA 0.53 As Princess Bubblegum prepares for war with Gumbald , Finn and Jake decide to pay him a visit so as to prevent it from happening . They meet with the Gum Family who are hellbent on wanting to destroy PB . However , when Finn saves Gumbald from falling , the family come on good terms with Finn and Jake and sign a peace treaty . Before leaving , Finn and Jake are doused with celebratory juice . When they get back to the Candy Kingdom , the juice turns out to be dumdum juice and turns Peppermint Butler into a baby . With no other option , PB sets to go to war with her uncle . Gumbald learns of PB 's survival and gathers many past villains throughout the series , including a confused Ice King , and prepares for the Gum War . 279 280 281 282 13 14 15 16 `` Come Along with Me '' TBA TBA TBA 2018 TBA TBD BMO narrates the Great Gum War in which Princess Bubblegum , Finn , Jake , Lady Rainicorn , Marceline , Flame Princess , Lemongrab , Huntress Wizard and Lumpy Space Princess band together to battle Gumbald and his army .

Question: when does the last episode of adventure time air
Answer: TBA