Child ' s Play Child ' s Play is the eighteenth episode of " " , making it the fifth episode of the second season . Synopsis . On " Destiny ' s Bounty " , Lloyd is wishing that he was able to play like normal children , but is made to train with the four other ninja to improve his combat skills . Lloyd manages to take down Kai , Jay and Zane , but is defeated by an attack from behind by Cole . Jay senses that Lloyd is distracted and asks him what is wrong . Lloyd tells the other ninja that the latest issue of the comic book Starfarer just came in , and was on a limited run . Lloyd asks them if he could go in to Ninjago City to buy a copy , but the other ninja say that as the Green Ninja , he doesn ' t have time for such childish things . Nya then comes on to the deck of the " Bounty " , telling the ninja that there has been a break - in at the Ninjago City Museum of History and that Lord Garmadon was spotted on the museum ' s security cameras . The four ninja set out to stop Garmadon , leaving Lloyd behind out of concern for his safety . The ninja , hiding on an upper level in the museum , watch as a group of Serpentine led by the tribal generals ( excluding Pythor ) move in to a room with a golden sarcophagus and a large skeleton on display . The generals talk about Garmadon , with Skales complaining that he hasn ' t successfully done anything since the Serpentine joined forces with him . Garmadon then steps out of the shadows , and all of the Serpentine bow to him , although Skales does so reluctantly . Garmadon describes to the Serpentine the Grundal , an extinct beast from long ago which was regarded to have been the most dangerous creature in all of Ninjago with its sharp claws and acute senses . He then announces that with the Mega Weapon , he will create the power to turn back time on the Grundal skeleton in the room , making it live again to hunt the ninja . When the Mega Weapon begins to turn back time on the Grundal , the ninja attack , successfully fending off attacks from the Serpentine . Kai throws his sword at the Mega Weapon , knocking it out of Garmadon ' s hand . Garmadon retrieves the Mega Weapon , and , believing that he failed to resurrect the Grundal , orders a retreat . However , the four Serpentine generals choose to steal the golden sarcophagus being exhibited , and slither away with it . The ninja pursue the thieves , but they manage to easily get away . However , the generals discover that the sarcophagus will not fit down the sewer pipe to be used for their escape , and are forced to abandon it . Wondering how the generals managed to get away from them so easily , the ninja eventually realize that they have been transformed into children , believing that the Mega Weapon had affected them instead of the skeleton . As they are discussing what to do , two Ninjago City police officers then arrive at the scene , and conclude that the ninja had stolen the sarcophagus from the museum . The ninja protest , explaining what happened , but the police officer do not believe them , thinking that they are " just a bunch of brats " . After a failed attempt of Spinjitzu by Kai ( and realizing they are too short to perform it ) , the ninja are then arrested , and told to return the next morning to the museum to explain why they stole the sarcophagus . The next day , Sensei Wu and Nya become worried for the ninja ' s long absence and decide to search the city for them . Lloyd is left in charge of the Bounty while they are away , who is more concentrated on the comic he was reading than training . Meanwhile , the ninja go back to the museum , and apologize to a member of the museum ' s staff for stealing the sarcophagus , so that they are able to be freed from police custody . The staff member accepts the ninja ' s apology , but asks what happened to the Gundal ' s skeleton . The ninja realize that the Mega Weapon must have succeeded in bringing the Grundal back to life , and escaped from the police by disguising themselves with clothes from the backpacks of other children on a tour of the museum . Shortly after the ninja escape , the Grundal leaps off the roof of the museum and runs off , causing panic to those in the area . The ninja then use a payphone to call the " Bounty " , and the ninja tell Lloyd to meet them at Buddy ' s Pizza with their weapons . The four other ninja tell a surprised Lloyd of the past events , and that the Mega Weapon not only brought the Grundal back to life , but turned them all into children , and that they need to find someone who knows how to defeat the Grundal . Lloyd says that he knows someone who does , and leads them to Ninjago Doomsday Comix , a comic book store owned by Rufus McCallister , also known as Mother Doomsday . Lloyd asks Mother Doomsday if he would know how to defeat a Grundal if one existed . Doomsday tells the ninja that the only way to destroy a Grundal would be with light , and recommends using an Illumisword , an illuminated sword - shaped weapon , to defeat it . Mother Doomsday shows the ninja authentic replicas of the swords , and Kai says that they ' ll take them . However , Mother Doomsday says that the sword can only be obtained by winning a comic book competition which is about to take place , so the ninja enter Lloyd into the event . Back on the " Destiny ' s Bounty " , Sensei Wu and Nya have returned from their attempts to find the ninja , and receive a message from Lloyd telling them what has happened so far . Wu and Nya then travel to Mystake ' s shop , and purchase a special tea , known as Tomorrow ' s Tea , which has the ability to make people older . Lloyd makes it into the final round of the comic book trivia competition , however he loses on the final question , because the question was about the latest issue Starfarer which the other ninja didn ' t let him go and buy . The comic book store then loses its electricity , and the Grundal attacks . Cole , Kai , Jay and Zane grab an illumisword each and attempt to defeat the Grundal , but the illumiswords have little effect and the Grundal knocks the four ninja down . Then , Lloyd attacks the Grundal by summoning a green ball of light , but the Grundal manages to knock Lloyd down as well . Then , Nya and Sensei Wu run into the comic book store , and Wu throws Jay the bottle of Tomorrow ' s Tea , explaining that if he uses it , it will turn the Grundal back into a skeleton and make the ninja older . But , the ninja realise that it will also age Lloyd and that he ' ll miss out on the rest of his childhood . The Grundal attacks again , and the ninja except for Lloyd are all knocked down again , with the Tea falling out of Jay ' s hands and Lloyd catching it . Lloyd then uses the tea , which successfully turns the Grundal into a skeleton , and restoring the four ninja back to their normal age . Lloyd then gets up , revealing himself to be older as well , with new hair , a deeper voice and longer legs . As the ninja leave the comic store to continue Lloyd ' s training , Mother Doomsday offers his last comic issue of Starfarer to Lloyd , saying he deserves it . Lloyd , however , declines the offer , saying he already knows how it ends and so joins the others outside . The last image is what seems to be Mother Doomsday ' s latest comic issue , entitled " Green Ninja " , which reveals Lloyd facing his father in battle . The two police officers were eventually arrested for accusing the Ninja of stealing the sarcophagus .