The Defenders' secret training is interrupted when an earthquake signals that the monstrously evil Megalith is breaking free. Their mentor, Professor Alnar, reveals to them that their training will not be completed. They must immediately embark on a dangerous mission to re-imprison the Megalith by recovering the four Pure Stones.
On their way to the Monastery of Amos-Yan to recover The Key, a device that will lead them to the four Pure Stones, the group is ambushed by a band of thieves. The inexperienced Defenders find themselves trapped and only escape with the aid of the roguish and mysterious Adam. Seth is skeptical of this mysterious newcomer and suspects he's a thief as well, driving him away. Meanwhile, agents of the dreaded Order of Infinis, an evil organization intent on the release of the Megalith, arrive at the monastery ahead of the Defenders and ransack the place.
The Monastery burns as Malco and Flinch tear it apart looking for The Key. With the help of a bizarre creature, the Defenders sneak into the monastery and split up to find the Key. Meanwhile, Adam runs into the beasts from earlier and requests that they give him back the Nova Stone. Seth and Kara find the Elder Priestess of the monastery, who leads them to the Key.
While travelling with Adam, Seth becomes annoyed at him and challenges him to a duel. While they're away Mel, Eric, and Kara are attacked by a bounty hunter, Snare.
The Defenders come across a carnival. The circus misfits end up controlling Erik through an amulet. Mel goes to investigate and it turns out that both the circus members and Erik are being controlled by another creature.
For the first time in their lives, the Defenders find themselves on the high seas, where they discover that their Di-Gata stones don't work over water. When bandits attack the ship they are traveling on, their friendly captain proves to be more than he appears.
A walled city held in the grasp of a ruthless dictator has a dark secret: its own citizens are being used as energy for the General Hod's crazed ambitions. For Kara, the situation becomes personal when her Guardian, V-Moth, is taken prisoner.
The Defenders learn the hard way that looks can be deceiving when the attentions of a pretty girl lead the group to face destruction in a village where, literally, nothing is as it seems.
Deep in the bowels of an abandoned mine, the Defenders uncover a secret: the existence of a Ninth Sigil. And it doesn't take long before the evil Lord Nazmul sends his agents Malco and Flinch to claim it for the Order of Infinis. Moreover Kara's boots start to malfunction.
The Defenders try to find a place to rest for a while but everyone they encounter slams their doors in their faces. The reason is that the citizens blame them for the recent rash of food robberies, while the real culprit pretends to be the city hero.
Deep inside a mountain at the roof of the world, the Defenders encounter Brim, the original carver of the pure stones, now living in self-imposed exile and under siege by evil creatures, the Gisli.
The Defenders close in on the first Pure Stone. Their quest takes them to a remote jungle village where Erik is hailed as a Shaman for saving a girl from a waterfall. As they try to gain information from the tribe about the Pure Stone, the defenders run into Malco and Flinch.
The Defenders find the way to the Dako Pure Stone, and eventually find themselves in a maze. Mel sees the Stone and picks it up, only to have it practically take over her body. But when the others find her, the Dakonauts (Lord Nazmul's unstoppable robotic army) attack them.
Mel and Erik have eluded their Sand Nomad pursuers and are hiding out while Mel recuperates. Seth has struck a deal with Doku, a former member of the Order of Infinis, who promises him the location of Nazmul's secret keep in exchange for Seth's word that he will destroy Brakus.
On the run from Malco and Flinch and the Sand Nomads who have overrun the Dojo, Mel and Erik encounter Bo, a brash young boy who tells them of a warrior cult competition being held in a nearby county. They quickly realize the trophy is nothing other than one of the prized pure stones.
Mel dreams of a long lost monastery and a pure stone hidden there. Nazmul is able to read her dream and decides that it is Mel whose body he must have as the host for his incorporeal being. He dispatches Malco and Flinch to kidnap Mel, unaware that Brackus has stolen Nazmul's key and has gone to the monastery for his own purpose.
Adam charms his way into the Defenders’ encampment only to steal away in the night with their pure stone. His trail leads the Defenders to a den of thieves where an arms auction is being held with the pure stone as the main attraction.
While heading for the legendary Nexus, a traditional place of healing, the young heroes meet Raald who claims to be a Defender escaped from Brackus' dungeons.
On their way to the Pinnacle, the Defenders face the Obelisks, an army of war machines created for Nazmul by Flinch. Erik and Kara stay behind to try to stop the destruction while Seth and Mel head for the Pinnacle to hopefully cure Mel of her wizard attacks. At the Pinnacle, Seth must face Omniaxor, his father’s Guardian.
The Defenders discover The Machine of Binding and Erik devises a plan to re-wire the machine to enable it to draw the pure stones to it. Flinch and Malco attack them, while a strange metamorphosis is taking place within Seth.
Nazmul's secret quest for immortality brings his subordinates to an underground palace which once housed an ancient King who is rumored to have achieved eternal life. The Defenders arrive at the palace looking for Kara, who has been taken by someone.
Seth deserts the Defenders and head towards a Dojo to get an advice from professor Alnar about his condition. While looking for him, the Defenders stop to help a caravan of refugees fleeing the countryside directed to the safe village of Arboth.
The Defenders locate the Yin pure stone in the sacred floating city of Callisto but the presence of an invincible Guardian makes the mission almost impossible. The Defenders learn that only the Nova Stone would help them, but this stone is not in their possession.
In a surprise turn of events, Adam shows up at Brackus’ safe house with the four pure stones and Kara all tied up. Kara is grabbed and prepared for the host body transfer that will give Nazmul physical form. The Defenders prepare for the assault on the castle.
Brackus controls the Yintos Army and his only goal is to release the Megalith. The Defenders ask for Professor Alnar's advice about their mission true consequences, then they head towards the Place of Binding. Now the final battle for control of RaDos rages on.
With the Order of Infinis shattered and the Magalith released from his prison the Defenders head to a nearby farm to recharge their stones while Seth stays to see what they're up against. Not too far from there a young boy observes the scene.
The Megalith has been destroyed and the new defender Rion joins the group. While the group is helping the citizens of Arboth to rebuild the city, Zad captures Kara that is brought to the Dark Realm.
Malco and Flinch attack the Defenders and stole the Nova Stone from them. But they are in a hurry to save Kara from the Dark Realm before the Equinox, so Seth decides to put off the issue. Meanwhile Brackus betrays Kara and tries to escape first, but is left to contend with the wrath of Leizel.
The Defenders find their new dojo, but it turns out that it needs a little work and cleanup. Erik and Mel are in the library when they find a receiver stone, which has recorded Doku and his fellow warlords in their discussion about taking over RaDos. When they arrive Rion's impatience causes a battle to break out, leaving Seth poisoned at the hands of Doku. They follow a rumor about a mysterious healer, with the power to cure anything.
A monstrous guardian appears at the dojo; while the Defenders are about to fight it, Bo shows up presenting it as his new guardian. They learn that Bo acquired it from Si'i, a black market guardian salesman.
The Defenders must now recover the Nova Stone stolen from Malco and Flinch so, while Erik and Rion are left to train at the dojo, Mel and Seth go on their search. But Kid Cole comes back and takes over a mining town, forcing the peolpe to extract Dakocite for him.
The Defenders and Brackus reunite at Port Reevus. They are now on the search for Brim, who is imprisoned on a far island. The Defenders get to him first and free him but then they have to fight against a dangerous creature named Yar-Maroth, so in the meanwhile Malco and Flinch manage to escape with Brim.
The Ethos use their power to merge together in Malco's body. Meanwhile, the Defenders try to find the cause of Rion shape-shifting into dark incarnate. Melosa has a vision that shows her the location of the temple of Yan-Sumos, where the Wizards of Yan first banished the Ethos, so the group leaves the dojo to find answers.
Erik, Rion and Brackus come upon the wreckage of the monastery where thankfully Seth and Mel have survived the collapse. Meanwhile, Malco and Flinch order all Zads to take care of the remaining Defenders. Mel finds an Eternity Stone and Brackus and Rion explain that the Wizards used those to travel through time. Everyone think that it's too dangerous but Mel does not heed their warnings, and travels back in time to the siege of Yan-Suma, when the battle against the Ethos is ongoing.
After a dispute about Brackus, Seth decides to leave Rion at the dojo and brings the other defenders with him to check out a distress signal. The Zads kidnap Si'i from the Gatashin Prison in order to get information about modifying his Guardianizer. Malco realizes that Rion is a large threat so wishes to get rid of him by transforming him into a guardian. While the Defenders are still away, Rion responds to another distress signal, which turns out to be a trap.
Mel finds out the location of the first Icon, but then a distress signal leads the Defenders to a port city where they meet a man shooting at a Sigil Slayer, which is eventually defeated. Von Faustien tells them that after the war against the Ethos left him whit no family he dedicated his life to hunting down those Ethos war dogs. Then he shows them to the tomb of Yan-Mara where the first Icon is located, only to find that a woman, Lady K'tash, has gotten there first and is waiting for them.
Kara sneaks in Ethos base and steals the Orb of Ogama-Yan. Meanwhile Seth manage to activate the Wizard Stones and has a vision of a swamp, but when the Defenders arrive at their destination they sink into the ground. There they meet Geo and her grandmother who live underground and secretly guard the second Icon.
Lady K'Tash awakens a giant golem and implants a Champion Stone in Seth's hand, hampering his healt and his possibility to cast. The Defenders need Brackus' help but, after traveling to a desert town, they only can find another healer who turns out to be actually Adam. Meanwhile Atagor-Am traces the Defenders down, attacks them and carries off Mel.
Doku and his cohorts, whit Adam's help, reactivate an ancient tower of the Wizards of Yan that is able to absorb Rados energy. Meanwhile, Seth is having a hard time adjusting with his new condition. When the Dojo's systems detect the tower, and Mel, Erik and Rion leave to stop it, Seth tries on the unstable mech arm that Erik was designing for him.
Kara comes back to the dojo, but she acts very strangely and not her normal self: she disregards Seth's leaving and doesn't seem to be disturbed by Brackus' change of heart. Meanwhile Seth meets Aaron, a former soldier of the Yin-Tos army, who host him in his house and offers to help him with his condition.
A noble girl named Lydia calls on the Defenders for help when she is suddenly attacked by the Amphitigons; Mel, Erik, and Adam rescue her but she tells them that the Amphitigons have stolen a precious Heart Stone and captured her brother. Seth and Rion are back to the Dojo, but while testing out the new mech arm Erik has made for his friend they are attacked by the Zads, who have managed to avoid the security system.
Lady K'tahsh plans to capture Si'i by using Melosa as a bait to draw him towards the village, but Rion saves her in time. Seth, Erik and Adam have just arrived back at the dojo from their mission when Kara insistently asks again about the Tome of Al-Mortagar, but Seth doesn't have time to pay attention to her.
Kara is held hostage by the Mortagarians in their underwater lair because they want the Tome of Al-Mortagar in exchange of her life. The Defenders have two days to bring it to them but the Tome is guarded by the Ogaman Federation.
The soldiers of the Ogaman Federation, led by Bo, arrests Erik for destroying the Tome of Al-Mortagar. While being visited by the other Defenders, the Wizard Stones give him a vision revealing that the third Icon is hidden in the prison and is guarded by a legendary creature.
Erik travels to an ancient temple with hopes of bringing Kara back. The other Defenders decide to storm Mount Froza but find out that it has been abandoned; there Rion accuses Adam of being responsible for Kara's death. In the meantime Malco, K'Tash, and Flinch get to a floating cave, where they sacrifice a young woman with an Ethos spell to create a new base.
The Defenders (except for Adam) investigate the recent disappearance of some children from a village. Since they can't find any clue about what happened, Rion offers himself as a bait, but he also vanishes in a bright flash.
Mel has a nightmare where Kor attacks her. Right after she wakes up and the others comfort her, the Wizard stones surround Rion, giving them the location of the fourth Icon. Erik decides to stay behind to monitor things and carve new stones. The others make it to the Pinnacle but Kor had also arrived.
K'tahsh finds out that the four Icons are in possession of the Defenders. Brackus is training the kids in combat when he meets a small pet of the kids which sprays a toxin in his face. Seth, Mel and Rion return to the Dojo and the wizard manages to clear the substance away with her powers, but the toxin makes Brackus fall in love with her. Meanwhile Erik realizes that the material he uses is unsuitable for the stones of the Lost Sigils, so he goes to collect Dakocite from the mining town.
The Defenders discover that the Von Faustien's Ethos parasite is missing from the vault. Brackus is training Roodu and Azura; when he leaves them they talk about something dangerous they stole and decide to use it to see what it can do. Maia arrives at the Dojo with a whole group of kids wanting to be Defenders.
Thanks to a dream Rion leads the others to the Spell Zone, where the fifth Icon should be. Suddenly a group of men attack them, until the sphere they found near the mine falls out of Seth pocket. Then the weird people cease to fight and worship the sphere as the portal Key, leading the Defenders into a Wizard Tower. Meanwhile Maia and Roodu are employed by Brackus for an underwater mission: they have to retrieve the other Icons hidden in the spaceship under Lake Maki.
The Defenders are erecting barricades around the Dojo since they expect an attack from the Ethos. Seth goes out for a recon mission, Erik and Melosa keep reinforcing the defences, while Rion demands that they remove the restraining sigil from his head. Erik doesn't know how to do that so Rion asks for Mel's help, who decides to use her wizard powers on him. At the Ethos citadel Malco orders K'tash to retrieve the last Icon so she leaves, riding on Si'i, to lead a legion of sigil slayers towards the Dojo.
Rion arrives at the Ethos citadel, his arrival seen by Maia. He tries to fight Malco but the giant simply awakens his Ethos side. He gives the last Icon, completing the Celestial Abyss. But Malco had no intention of freeing his brothers, just to simply feed on their energy and become a god. Meanwhile, at the dojo, the Mortagarians demand the Icons but Seth said that Rion took them. The leader informs him that Rion is a failed Wizard experiment meant to use Ethos-created warriors. Erik accepts that humans did invade Rados and offers the Mortagarians his Primordial stones as a peace offering and asks their help in defeating the sigil slayers, so they could build a new future together. The leader is pleased with such an act and allows Erik to use the stones in battle. But as the fight goes on, the Defenders and Mortagarians are overwhelmed and forced to fall back. Adam comes in and saves Mel, who was pinned down by rubble. When they try to retreat back to the dojo, their path is blocked by K'tash and Si'i. Erik uses the Primordial stones to seal K'tash beneath the earth, causing the slayers to go wild. The Mortagarians remain to deal with the rest of the slayers while the Defenders follow Si'i to Malco. Malco becomes alerted to their approach and sends Rion to stop them. With his skills, he nearly kills them but Adam uses the Phase Stone to remove the restraining sigil, bringing about his beastly form. His Ethos side tries to regain control but Rion returns to normal. Together, they go to face Malco. But Rion's encasement attack is simply repelled, throwing them against the wall. Malco prepares to destroy them only for his true personality to expel the Ethos from him. Angered at his betrayal, they kill him. Rion transforms into his other form and takes out two Ethos but the remaining one subdues, only to be attacked by Si'i, whom Rion was able to call in the ancient language. The Ethos simply turned him back to human and threw him out of the citadel. Absorbing tons
