While the firstborn cub of the monarch is destined to become the next Ruler of the Pride Lands, the second-born cub is tasked with leading the Lion Guard, a group dedicated to preserving the kingdom and defending the Circle of Life. As its leader, the second-born cub is expected to be the fiercest of the group and is thus gifted with the Roar of the Elders by the Great Lions of the Past. When the leader of the Lion Guard uses the Roar of the Elders, four of the ancient lions roar along with them, instilling extremely powerful sound vibrations in the cry. The Roar is strong enough to blast downward-falling water upward, scatter a pile of boulders, or force someone else backward, sometimes sending them flying miles away. However, if the Roar is used in anger, regardless of the intent, it can cause mass destruction and there is a risk of it rebounding like an echo, which can cause natural disasters such as earthquakes. When used in anger, the clouds will be dark and stormy.
The Roar can be controlled, if the user has faith in him or herself, allowing to direct the Roar's force as he or she wishes. Additionally, if directed at a cloud, the Roar has the ability to inflate it with water, thus causing it to rain for a short while.
The Roar of the Elders can be used to summon the spirits of the Great Lions of the Past, mostly when they are needed to roar, and, if used in anger, it can even summon the spirit of an evil lion from the past. Instead of in clouds, evil lions appear in fire.
Since the Great Lions of the Past provide the power behind the Roar, they control its use. It is to be used for good only and will be taken away if the user does not respect their gift and use it for selfish or malicious purposes, as was the case with Scar. However the gifted power is destined and expected to someday return to the Tree of Life.
As the leader grows the Roar grows in power, like keeping ocean water temporarily at bay to create a land bridge and prolong its use. A current user of the Roar can't only talk to the great kings of the past, but also other Lion Guard leaders, like how Kion is shown talking to Askari. When blasted downwards, the Roar can create ledges, cliffs, and platforms. Only by willingly giving up the Roar completely can one truly master its power.
If the user is inflicted with the infamous Mark of Evil, the neurotoxin in the cobra venom that is inflicted into the bite as a scar will slowly begin to change the user: It will give them brain damage as well as weaken or disorient them, and it will cause their darker, more uncontrollable impulses to begin to take over their actions and thought process, which puts the user at risk of becoming evil and using the Roar for nefarious purposes, or losing control of the roar. Should the user want to be healed, and regain their control of the Roar, they must travel to the Tree of Life to find the anti-venom.
Before the events of The Lion Guard, Askari was the first leader of the Pride Lands' Lion Guard and as the second-born cub of the monarch, he was the first one ever to use the Roar of the Elders using its powers to do great good. Askari discovered the Roar at the Tree of Life and discovered its powers there and managed to master it.
Then, Scar was the leader of the previous Lion Guard before Kion and possessed the Roar of the Elders, as he was the second-born cub of the monarch. However, the power quickly got to his head, and he thought himself more worthy of being king rather than his older brother, Mufasa after an incident in which Scar was given his nickname after a facial wound he received from a venomous cobra whom, along with a Strange Lion attempted to take over the Pride Lands before being defeated by Scar. So he tried to employ the rest of his Lion Guard to help him overthrow Mufasa, but when they refused, he destroyed them. Seeing this, the Great Lions snatched back the power, for they had intended that the roar is not meant to be used for evil.
Kion, the second-born cub of Simba and Nala, is given the Roar of the Elders. When his best friend, Bunga, is trapped by a pair of hyenas in the Outlands, Kion uses his power to free him from their grasp. The Mark of the Guard appears briefly on his shoulder, though disappears before Kion even realizes it was there. Back at Pride Rock, Rafiki and Simba happen to overhear the Roar, and they come to the conclusion that Kion is now ready to be the leader of the new Lion Guard.
After Kion assembles a team, he attempts to show them his powerful Roar, but the power refuses to work. However, the Roar returns to him in the final battle against Janja's clan, in which Kion uses the Roar to send the hyenas scurrying back to the Outlands.
After fighting off Janja and his clan, Kion tells Jasiri to get behind him as he uses his roar to defend both himself and Jasiri by blasting the hyenas away. The roar also worked as a powerful signal to alert the rest of the Lion Guard, who rushed to his rescue. Jasiri is amused by what she sees but also impressed that a lion saved a hyena.
When Bunga's quick and easy dam solution leads to the dam breaking apart, the waters that it was restraining spread rapidly over the Pride Lands. The Pride Landers flee but are eventually trapped, with rock walls on all sides of them and the floodwaters on another. Kion uses the Roar to move the water back, away from the animals, with enough force to push it over the side of the rock walls and create a waterfall.
When Janja, Cheezi, and Chungu trap the Lion Guard in a ravine by dropping boulders on either side of them, Kion uses the Roar of the Elders to blast the rocks away so that he and the Guard can stop the hyenas from attacking the zebras.
After Beshte accidentally knocks a boulder which causes the zebras to run straight into a fast flowing river leading to a waterfall, Kion leaps down onto a nearby tree branch and uses the Roar of the Elders to drive back the water and save the zebras from harm.
When Muhanga and Muhangus call Kion about a hyena infestation, Kion uses the Roar to drive aardwolves out of the Pride Lands, believing them to be hyenas. The force of the roar sends them flying into the Outlands.
When Janja accidentally slides down a slippery hill covered in mud, he winds up face to face with the Lion Guard. When Cheezi and Chungu join him and accidentally explain their leader's plan, Kion uses the Roar to force the hyenas back into the Outlands.
Later, Nne and Tano fool the Lion Guard into chasing some sable antelopes while they approach some oryxes. The Lion Guard arrive just in time to stop them and, as the hyenas predict, Kion uses the Roar to force them both back into the Outlands. Nearby, Janja comments that he is, for once, glad to hear the Roar, having been used by his fellow clan members.
Jasiri asks for Kion's assistance in getting her watering hole back from some lions who have stolen it from them. When he gets there, their leader, Zira, questions why Kion doesn't just use the Roar to give Jasiri the water she needs. Although hesitant, Zira is able to convince Kion to Roar at a cloud, which causes a brief rainstorm. Kion admits that he had no idea that he could do such a thing, and Zira offers to tell him more about the Roar if he follows her in private.
Later, Zira explains that she knew Scar personally and that they were very close. She tells him how Scar told her all about the Roar and its capabilities, and that he lost it when he used the Roar against his fellow lions. When she brings her children, Kovu, Nuka, and Vitani back, she explains to them that Kion is powerless without his Roar, and how he won't use it on them in fear of losing it forever. When the rest of the Guard arrive to save Kion, Bunga insists that Kion uses the Roar to despatch the Outsiders. Kion, however, tells Bunga that he cannot, since that was how Scar lost the Roar. But the honey badger reminds him that's not why Scar lost it, he lost it because he used it for evil. With that in mind, Kion uses the roar on Zira and her pride flinging them to another section of the Outlands.
Kion uses the Roar to blast Janja and his clan away from Nala. However, Kion's fury when he roared was so powerful that it rebounded, snapping trees and triggering an earthquake. Kion is evidently horrified by the damage that he has done. He observes the paintings of Scar using the Roar to destroy his Lion Guard and does not use it to move some rocks blocking the giraffes' watering hole or to save a klipspringer stranded on a rock. Instead, he finds different methods.
Makuu hears of this and uses the condition to his advantage, expanding his territory to the Flood Plains now that he no longer has Kion's roar to fear. Kion speaks first to his mother, then Makuu, whose crocodiles pull Nala into the water, using her as a shield. Kion almost unleashes his rage in the form of the Roar, but controls himself, instead of discovering a powerful new way to use the Roar. He directs it in individual waves, avoiding his mother but taking out the surrounding fleet and flinging them away.
While escorting Bupu's Herd to safety, a rock slide on the side of the cliff separates the herd from the Guard. The Lion Guard quickly climb over the rocks. When Bunga assures the herd that Kion has 'got this', Bupu and his herd still refuse to move. Before he can finish his statement to Bunga, Kion uses the Roar of the Elders to blast the rocks away, reopening the pathway for them to continue to the Flood Plains. Although hesitant, Bupu and his herd finally move.
When the hyenas attack the baboons and the elephants during the Dry Season, Kion uses the Roar of the Elders to send them flying towards the Outlands.
Later, Janja and Ushari discover that they can bring back the evil lion Scar by getting Kion to Roar over the volcano (and by using a Bakora Staff). After luring him into the Outlands by kidnapping his sister, Janja provokes Kion into using the Roar of the Elders in anger over the Outlands' volcano (by threatening to end his family) which causes the volcano to erupt. The Lion Guard leave straight after.
Although their plan to bring back Scar seems to have failed, Janja throws Makini's staff into the volcano in a temper and thus finishes the ritual, summoning Scar.
When dry lightning strikes a fire around a small enclosed area, Kion and the Lion Guard work fast to save the animals inside. After Beshte has knocked down a rock to create a path out, the animals escape, leaving Kion to use his Roar and put out the fire entirely.
When Kenge, Janja, Cheezi, and Chungu try to steal some Tikiti Melons, Bunga and Makini stall them while the rest of the Lion Guard recover from one of Kenge's paralyzing bites. Before Kenge can hurt Bunga or Makini, Kion arrives at the top of Embamba Canyon, where he uses the Roar to send them back to the Outlands while Bunga and Makini hide behind a rock, safe and sound with the melons intact.
As Kion and the guard rescue Zazu, when he gets captured by Janja and his clan in an attempt to interrogate him for information about Simba. During the fight, Zazu sees that Fuli get cornered by two hyenas and backed up into the lava (unknown to her). The hornbill gets his cage rolling and saves Fuli and almost falls into the lava himself but Kion notices this and uses the Roar on the lava to create a small spot where Zazu's breaks free and flies away to safety.
After Kiburi and his float are beaten by the Lion Guard and Makuu with help from Hodari, Kion uses the roar to send them flying back to the Outlands, though not before Kiburi warns Makuu that it's not over.
When surrounded by Scar's army, Kion prepares to use the Roar. Scar warns him of the dangers of using it in a volcano, but the cub replies that he doesn't know as much about the Roar as he thinks. Kion successfully uses the Roar multiple times to escape.
When the vultures attack Makini, the Lion Guard quickly save her, and Kion uses the Roar for the last time that day by sending Mzingo's parliament back into the Outlands.
When Kion and Simba consult with Mufasa on Scar's return, Kion blames himself. As he is about to tell Mufasa how he used the roar in anger again, his Grandfather reminds him that the Roar is a power used for both Good and Evil, seemingly disappointed in him.
Tamka and Nduli proceed to use their tails to tickle the Guard's tummies as told by Thurston, but it doesn't take long for Nduli to notice that their plan isn't working. Knowing the reason they're acting strangely, Kion eventually grows tired of their antics and uses the Roar to send them away.
The Lion Guard arrive in the Outlands to help Jasiri's clan out from Scar's army. Kiburi confronts to Kion that the army refuses to leave without first defeating the Hyena Resistance. However, Kion uses the Roar to send Janja's Clan, Reirei's Pack and Kiburi's Float further away into the Outlands.
Janja, who got knocked by one of Kiburi's members and slips closer to the lava of a steam vent, gets pulled out by Jasiri. When she tells him for his clan to join hers, a speechless Janja hesitates, then dismisses Jasiri's offer and runs off. Shupavu and Njano, who both secretly watched all the time, question about Janja's hesitation and decide to report it back to Scar.
Ono warns everyone that Scar's army is back in the Pride Lands going after some Sable Antelopes. Kion suggests that they cut through Nyani Grove. Shujaa decides to make a path for them to walk through but he didn't know that baboons live in the trees that he cut down. The baboons start run along with the buffaloes Kion orders Fuli and Beshte to calm them down. Ono moves the Sable Antelopes away from the army and Kion uses his roar to blast the Outlanders away. Shujaa was impressed and thought that Kion's roar was the best thing that he ever saw.
Kion bestows both the Roar and the Mark of the Guard onto Vitani so she can be the official leader of the Pride Lands' newest Lion Guard, and by letting the Roar go, he truly mastered it. Kion afterward demonstrated the mastery of the Roar to Vitani and the other Pride Landers by lifting Pride Rock. Kion brought the Roar back to it's home at the Tree of Life.
If the reader chooses Fuli's ending, Kion uses the Roar of the Elders to blast away Makuu's float after rescuing Zuri from them. The Roar smashes some nearby logs, which end up forming a dam that allows Zuri and the Guard to return home.