While the premise is not bad, the execution is just painfully bad.
Mum-Ra decides to lure Lion-O into the kingdom of webs. He Disguises himself as Diamond-fly, and hypnotizes Lion-0.
Snarf follows them carrying the sword. He is then captured by a spider after Mumm-Ra's hypnotism wears off of liono, and he uses the sword to on Diamonfly to reveal Mumm-Ra's true self. Lion-O goes off to resce snarf, and faces off with some spiders, one of which speaks a lot like Jackalman. He moves on, and is about to rescue Snarf, when suddenly Spydera, the new queen of the Kingdom of Webs, appears. He summons the other Thundercats, and is then captured by the Spydera. He looses the sword in the fight and it gets stuck in the ground. Well the writers conveniently forget he can summon the Sword to his hands, and so he patiently waits for the others to arrive, and throw it to him. While this is going on, we get some nice animation of the other Thundercats fighting Spydera and loosing. In one of these the Thundertank gets stuck in the webs, and although Tigra and Cheetara, are now wrapped in webs, Panthro makes no effort whatsoever to get out of the tank to help them. He patiently waits until Tigra manages to throw the Sword to Lion-O, he frees himself, does the Thunder dance, and as everybody is now empowered they free themselves. Somehow the Tank is now free too. Snarf mysteriously frees himself, so mysterious its even acknowledged by him and the Thundercats, yet no explanation is ever given o how he did it. Other than saying, "You have to dig deep enough".
This is one sad episode. Fortunately its not often we get them this bad.