Trials of Lion-O, Part 2 is the sixteenth episode of ThunderCats 2011 TV series.
Back in the spirit world, Lion-O must now face a test of strength against "Panthro," where he must knock Panthro out of a ring before the sands within the hourglass run out. At first Lion-O tries to ring-out Panthro by brute force. When that fails, he remembers that he is the king and simply orders Panthro out of the ring, which he does. At first Lion-O is confused, Panthro then tells him that the "strength" he needed was the strength to give orders with conviction. Meanwhile, the Cats quietly took out the Lizard guards and they enter the ship. Unfortunately the alarms go off and alert more Lizards. Cheetara asks Tygra what they should do but Tygra can't seem to come up with a plan. But then Wilykit quickly charms the guards with her flute long enough for the others to slip past. The guards forget what happened and believe that the intrusion alert is a false alarm.
In his final trial, Lion-O ends up going up against "Tygra" in the same arena where he'd previously lost to the real Tygra before the fall of Thundera. In order to get the final key and regain his life, "Tygra" tells Lion-O that he must beat him to the bell and the race begins. Lion-O quickly realizes it's a test of his control over his emotions after the fake Tygra taunts him. Unfortunately Tygra's taunts frustrate and destract Lion-O which causes him to lose to the fake Tygra.
Meanwhile, the other ThunderCats move through the ventilation shafts and find Mumm-Ra attempting to extract the Eye of Thundera from the Sword of Omens with a spell with his Lizard Priests. Despite opposition of his decision, Tygra decides to attack in attempt to retrieve the Sword of Omens. Mumm-Ra uses powerful magic to neutralize all of them and has them detained.
In the spirit world, Jaga tells Lion-O that he failed the tests and that Mumm-Ra has obtained the Sword of Omens and captured the ThunderCats. Desperate to save them, Lion-O offers his soul as in exchange for a chance to return to the living world. Jaga tells him that the Spirit Stone will return him to his body. He'll then have until sunrise to stop Mumm-Ra and save the other Cats, after that his soul will be sent to Limbo for all eternity. When Jaga asks if Lion-O understands the consequences of his choice, Lion-O accepts. He awakens underwater, the Spirit Stone frees him from the rocks and he makes his way to the surface. While Lion-O laments how far he'll have to climb, he happens to spot a large Pterodactyl-like beast fishing nearby. He then grabs onto the flying animal in order to get up the cliff. Spotting the drawings left by Wilykit, Lion-O follows her trail until he reaches Mumm-Ra's temple.
Within the holding cells, Tygra is unsure of the next move and regrets questioning all of Lion-O's decisions since they always worked out. While the others are in doubt, Wilykit still thinks that Lion-O will come for them. Sometime later, Lion-O infiltrates Mumm-Ra's temple, where he finds Slithe, Kaynar, and Addicus. Lion-O manages to trick them into one of the cells and proceeds to free the other ThunderCats. The group is happy for his return, but also curious how he managed to survive. Lion-O tells them that there was no time to explain and he told them they need to focus on reclaiming the Sword.
Mumm-Ra makes a second attempt to remove the Eye from the Sword until Panthro blows down the door. While the other ThunderCats fight the Lizards, Mumm-Ra transforms and battles Lion-O, who uses the Spirit Stone's power to block Mumm-Ra's attacks. Lion-O successfully reclaims the Sword of Omens and uses its magic to weaken Mumm-Ra. The ThunderCats then escape from the ship to a safe distance. As the sun begins to rise, Lion-O tells everyone that he must go. Baffled by his words, the others want answers and Jaga's spirit appears and explains Lion-O had paid the ultimate price, but he will not have to die. Jaga explains the trials were not only ment to test Lion-O's skills, but also his heart. Lion-O is given a second chance at both life and leading the ThunderCats to victory. Still confused over what's happened, Lion-O begins to tell the group about his trials, starting from his death.
- The third trial takes place in the Thundarian Palace while the fourth one takes place in the Game Arena.
- This is the second episode in the series so far where it starts with a recap of the previous episode, "Trials of Lion-O, Part 1."
- The trials Lion-O faces are similar to the Anointment Trials from the Original series, mainly Lion-O's Anointment First Day: Trial of Strength where he has to face off against Panthro and Lion-O's Anointment Fourth Day: The Trial of Mind Power where he has to test his mental strength against Tygra.