Anointment Trials are a series of special courses that every Lord of the ThunderCats must participate in. These trials originated on Thundera and form an important part of the ThunderCats' tradition. Since the leadership of the ThunderCats is hereditary and passed down from father to son, the trials are a way of determining if the holder of the title is truly worthy of it.
While never mentioned explicitly, it would seem likely that Claudus also underwent the Anointment Trials on Thundera before he became the legitimate Lord of the ThunderCats. After his supposed death in the destruction of Thundera, Lion-O automatically inherited the title. It was not until Lion-O's 20th birthday that Snarf told him about the Anointment Trials that he must partake in.
Starting on his birthday, Lion-O had to undergo five trials over a course of five days. The rules of the trials which must be followed are:
- Lion-O cannot use the Sword of Omens or the Claw Shield in the trials.
- Lion-O cannot accept any kind of help from any other person.
- The other ThunderCats are forbidden from assisting Lion-O directly in any way during the course of the trials.
In Lion-O's first trial, he had to prove that he was stronger than the mighty Panthro. After spending the entire day overcoming a variety of dangers and obstacles that he faced en route, Lion-O finally reached Panthro at sundown. The two fought and Lion-O eventually proved to be stronger. Panthro then handed Lion-O his belt insignia as a sign that he had won the trial against him.
For his second trial, Lion-O had to be faster than Cheetara in reaching a set finish line. Cheetara took the longer easier route while Lion-O went for the shorter more dangerous route. In the end when they have just five more miles to cover to reach the finishing line, both Lion-O and Cheetara sprint at full speed. Lion-O wins as Cheetara is unable to maintain her top speed for more than two miles even though she initially took the lead.
The third day of the trial saw Lion-O go head-to-head against WilyKit and WilyKat in the Maze of Infinity. The ThunderKittens, who are fully familiar with the maze, set up a number of booby traps and tricks to lead Lion-O astray and ensure that he never reaches the exit of the maze in time. Things are further complicated by the arrival of Monkian in the maze as well as the ThunderCats' discovery of the Under-Earthmen. Once again, Lion-O shows that he can be wilier than the twins and wins this trial as well.
The fourth trial pits Lion-O against Tygra who uses his mind power to create a host of illusions to confuse and terrify Lion-O. The Mutants also make the trial even more difficult for Lion-O but he finally is able to focus his mind, overcome his fears and win the trial.
For his fifth and most dangerous trial, Lion-O must face his greatest enemy, Mumm-Ra. After successfully making his way into the Black Pyramid, Lion-O fights Mumm-Ra alone and, after learning that the mummy's sarcophagus is his source of power, tosses it into the cauldron, defeating Mumm-Ra and successfully completing all his five anointment trials.
A grand coronation ceremony is held at Cats Lair where Cheetara places the crown of the Lord of the ThunderCats on Lion-O. A number of the ThunderCats' friends and allies attend the ceremony and cheer on as Lion-O finally earns his title.