If you grew up watching these shows then you are going to want to read these comics. If you didn't watch these growing up you will still love these comics because Daivid and Goldfine do an amazing job giving you just enough back story to fill you in with out bogging down the story. I personally do not know much about He-Man except the basics but I am following along just fine!!
Once again, Williams' II artwork is breath taking and if you want to see more of his work check out his Batman Ninja turtles crossover which was equally as awesome.
The ancient spirits of evil that inhabit the tomb of Mum-ra are fed up!! They grow tired of his constant failing at defeating the Thundercats. So they order him to find a sword of power in order to defeat them.
Mum-ra summons Eternia (He-Mans world) to his realm starting a rift between worlds that is tearing apart the planets. Prince Adam realizes he needs to help and is going to transform into He-Man but before he can the Sorceress stabs him through the chest with the Sword of Power. The Sorceress was actually Mum-Ra in disguise and he disappears with the sword.
Turns out that Skeletor had made a bargain with the Spirits of Evil by agreeing to set them free of the Black Pyramid in exchange for the Sword of Power, which is what he always wanted in the cartoon and justifies how this cross-over is possible.
Skeletor, who is a complete badass in this book, kills Mum-Ra and drinks his remains in order to become "ever-living". He needs to do this because he isn't powerful enough to summon the power of Grey Skull like He-Man. Mum-Ra however is not completely gone, he is within Skeletor.
Back on Eternia He-Man is in a battle with Evilyn and company and when Skeletor summons the Power of Grey skull. This causes He-Man to turn back into Prince Adam,dead, with a gaping hole in his chest.
At snake Mountain, Skeletors lair, he plans how he is going to take Castle Grey Skull when Lion-O and the Thundercats bust in and fight him. This battle is epic! Two swords of power in one fight! Lion-o eventually uses the Sword of Omens to show Skeletor his reflection and disappear in a flash of light leaving the Sword of Power Behind.
The lose of the Sword of Power returns Skeletor to his original form and the spirit of Mum-Ra leaves his body as well. Mum-Ra feels it would be best if they work together and attempt to get both swords of power. If they succeed then they can finally be released from the spell of the potion that skeletor drank earlier, made from Mum-Ra's remains.
The Mum-Ra and Skeletor use the Gold Disks of Power to enslave the Spirits of Evil and go back to Castle Grey Skull to retrieve the swords.
Lion-O gets the idea to resurrect Prince Adam using the Black Pyramid as Mum-Ra does. When he gets there with Adam and Cringer all of the baddies of both worlds are plundering the pryamid. Lion-O transforms Cringer into a Thundercat and he f*#ks up everyone. One of the best moments in the entire book is seeing Cringer as a Thundercat!!
He man places Adam in a sarcophagus and resurrects Adam but he is possessed by the powers of evil and fights Lion-O in an unbelievably beautiful battle. It goes back and forth but they are equally matched. Lion-O is about to strike Adam when the possession passes and he is returned to normal. Lion-O sees a vision with the Sword of Omens and sees the Thundercats enslaved or dead on a battlefield outside of Castle Grey Skull.
We pick up at the battle for Castle Grey Skull where the Spirits of Evil are attacking the Etonians and the Thundercats.
Jaja appears to Lady Sorceress and asks her if she can help him find an ancient Thundarian artifact that he believes can help win the fight against Skeletor and Mum-Ra. They return to Eternia with a Thundarian chest that holds a Disk of Knowledge that can reveal and make vulnerable the Golden Disks that Skeletor used to awaken the Ancient Spirits of Evil. Now is the time for the Eternians and Thundercats to strike and destroy the Spirits of Evil once and for all!!
They are successful in defeating the Spirits of Evil but not before Skeletor and Mum-Ra summon them once more to become Mum-ator. Which is a giant Skeletor with the head of Mum-Ra.
Lion-O and He-Man finally get to the battlefield outside of Castle Grey Skull only to find their worst nightmare. All of their friends appear to be dead or close to it. Adam's father as well as Cheetara are both holding on to life but it looks bleak. The two warriors rush inside the Castle where they find the Sorceress under the foot of Mumm-ator who is in possession of the Orb of Power. The Castle was built to protect the orb and only He-Man's sword can unlock its power.
He-Man and Lion-O fight Mumm-ator back and fourth. Getting the orb,losing the orb and each time traveling to alternate dimensions of their home worlds, and even combinations of them as well.
Eventually, Mumm-ator gets both the Orb and the Sword and begins to open it when He-Man and Lion-O figure out to combine the strength of their swords to defeat him.
In the end the Thundercats must return to to Thundera before their portal closes and all the big characters from each team exchange pleasantries and mementos before they leave.