The Sword of Plun-Darr was used by Ratar-O when he and the Mutants tried to take over and enslave the inhabitants of Thundera. Jaga battled Ratar-O using the Sword of Omens, which he had already used when Ratar-O was using his Rat's Eye daggers. Jaga ended up beating Ratar-O and to his Sword of Plun-Darr, which he threw in a volcano. Instead of destroying the sword, it sank to the core of the planet and caused the planet to explode. Later, Ratar-O reattained the sword in the planets debris.
Ratar-O with the sword came to Third Earth, seeking to destroy the last Thundians and take over the Mutants. He single-handedly defeated all the ThunderCats with the Sword of Plun-Darr. Later, on the Rastar, the mutants joined the ThunderCats to fight Ratar-O, but first launched the Sword of Plun-Darr out of the ship via ejector seat. This sword ended up floating in space near Third Earth.
Mumm-Ra, looking for a item to defeat the ThunderCats, was advised that that weapon would be the Sword of Plun-Darr, which crashed into his Black Pyramid. Mumm-Ra used it to get large and to recruit the Mutants. After Mumm-Ra had some fun bullying the Wolo Village, the ThunderCats came to stop him. He revealed to them that he now had the Sword of Plun-Darr and started using it on them. They ran back to Cats Lair to find the Mutants had control of it. As they thought of fleeing, Mumm-Ra used the sword to destroy the ThunderTank. After that Mumm-Ra took the ThunderCats weapons other than Lion-O's sword and he fought Mumm-Ra. However, Mumm-Ra revealed that he could make himself bigger with his sword by simply saying Plun-Darr. Lion-O's sword and Mumm-Ra himself grew larger and larger, but eventually the Sword of Omens was too big for Lion-O to wield properly. After Lion-O's defeat, Mumm-Ra used the Sword of Plun-Darr like a golf club and hit are the ThunderCats to they all fly a far distance.
Later, the ThunderCats took back over the Cats Lair and turned on "Thunder-King-Battle-Lord", turning the Cats Lair in a megazoid. They were at first not doing well, as Mumm-Ra still had the upper hand. Once Lion-O figured out that the Thunder-King-Battle-Lord could hold the sword with him controlling the sword itself, Mumm-Ra all the sudden began to lose. In his defeat, the Sword of Plun-Darr was taken by the ThunderCats, leaving Mumm-Ra back in normal mode, and flung back to Black Pyramid. Lion-O then broke the Sword of Plun-Darr in two, making it not able to work.
It is two machetes blades connected by a snake shaped hilt. The blades are very spikey.
Powers and Abilities
The Sword has caused the explosion of Thundera; so it is quite powerful, only to be defeated by the Sword of Omens. While in Ratar-O's hands it can pretty much fight like a sword in combat or as a laser gun. It's magic glow was green for Ratar-O. When gained by Mumm-Ra, he was able to get larger in size, along with the sword. The sword was shown to be able to lift rock and throw it at enemies, even making the levitating rock able to carry the holder of the sword. The sword also has the ability to attract objects, such as the ThunderCats' weapons. Note, in Mumm-ra's hands, it glows purple, like the Black Pyramid on the inside.