The Power Stones are a set of four powerful stones that gives whoever wields them ultimate power.
The stones must be infused with a weapon of mystical origin in order for them to deliver their full potential.
Long ago Lord Mumm-Ra began a search for the four stones. With the help of the ThunderCats (who were his servants at the time that accompanied on his ship, the Black Pyramid) he collected the first three stones of power and fused them with the Sword and Gauntlet of Plun-Darr, which he forged from the life source of a star and in doing so caused the destruction of an entire star system that lead to the death of billions.
Leo became the first Lord of the ThunderCats and managed to strip Mumm-Ra of his stones. During the battle and Mumm-Ra's downfall the Black Pyramid (Mumm-Ra's ship) crashed on Third Earth and the Power Stones were divided among the animals to prevent Mumm-Ra, if he should ever return, from obtaining them as the animals decided the stones were too powerful for one species to have. The Cats kept the War Stone, the Elephants took the Spirit Stone, and the Birds took the Tech Stone since all others had rejected technology but them. It has not yet been revealed who took the fourth stone.
Hundreds of years later, after the fall of Thundera and return of Mumm-Ra, Leo's descendant Lion-O lead a search for the Power Stones in order to defeat the Undead being, just as his ancestor did in the past. As of now Lion-O currently holds two of the four stones, the Eye of Thundera and the Spirit Stone.
- War Stone: a large red stone resembling a Cats eye and the most powerful of all the stones. When fused with the Sword of Omens or any weapon it is capable of shooting large red beams. It also gives its wielder the power of sight beyond sight (looking into the future).
- Spirit Stone: a diamond shaped pink stone capable of generating an impenetrable shield when fused with the Gauntlet of Omens. If fused with another type of stone in the Gauntlet of Plun-Darr it creates the Armor of Plun-Darr.
- Tech Stone: a disc shaped light green stone. When fused with the Gauntlet of Omens it creates the Armor of Omens.
- Soul Stone: a diamond shaped blue stone. So far it is unknown what power it yields, but it is seen that when fused with the Spirit Stone in the Gauntlet of Plun-Darr, it creates the Armor of Plun-Darr.