WARNING: This article contains spoilers for Invaders #7, by Chip Zdarsky, Carlos Magno, Butch Guice, Alex Guimarães and Travis Lanham, on sale now.
Marvel's recent stories involving Namor have more or less transformed him into a straight-up villain. From attacking Wakanda with the Phoenix Force to being beheaded for his ways by the Squadron Supreme, the benefit of the doubt kept getting slimmer and slimmer even after he was resurrected due to the Sub-Mariner's insistence on being an aquatic terrorist.
In Invaders, he's now haunted by the ghost of Tommy Machan, a dead friend from World War II, and this has led to a downward spiral with Namor launching chemical attacks on certain cities, turning surface-dwellers into Atlanteans who have no choice but to join his underwater kingdom. As he preps for retaliation from the Avengers, though, Namor levels-up his arsenal with a weapon that in the past was used to almost kill him: the Serpent Crown.
Namor's already facing a mental challenge, since some of his minions went behind his back and infected regions like Russia, which means Atlantis has even more refugees to take in. He simply wanted to tackle a few cities, but his soldiers want the entire world to pay. This led to conflict within the United Nations as various world powers argue about waging war, and Iron Man himself has lashed out at Captain America for not allowing the Avengers to pursue aggressive action, especially since Namor opposed them in Marvel's main Avengers title not long ago.
The toll is eroding Namor's sanity, because he doesn't know if it's Tommy's ghost who's guiding him in the right direction, or if someone else is playing games with his mind. Seeing insubordination from his soldiers has ticked Namor off and when he calls out his generals, they play to Namor's ego and offer him one of Marvel's most powerful relics rather than beg forgiveness or cower in fear. When he finally dons wears the crown, its corrupting influence is absolute and instantly visible in the Sub-Mariner's crazed eyes.
The Serpent Crown has been a big part of Namor's history since being created by Roy Thomas and Marie Severin in Sub-Mariner #9 in 1969. It was an artifact that belonged to the ancient serpent God Set and started a war between Atlantis and the Deviants and Set's Serpent People on Lemuria. It would be lost amid different civilizations over the years, with Atlantis and Lemuria both hiding it when they got sunk in the wars. For a while it also ended up lost in Antartica with Paul Destine finding it on an expedition with Namor's human dad, Leon McKenzie. Later on, Destine would wear it, try to take Namor out and rule his people.
The crown would eventually fall to Namor, corrupting him and his consort, Dorma, because it allowed Set to possess these people's minds. While it gave them psionic abilities to control millions of disciples and godlike abilities such as energy blasts, the power of illusions and the gift to manipulate matter and energy, it was all came at a hefty price, since the crown was merely a conduit for Set to control whoever was wearing it. In short, by wearing the crown, you simply became an avatar for the evil god.
Ultimately, Namor almost went amnesiac from it and came close to losing his entire kingdom. Set was so powerful that the crown almost killed Namor the last time he wore it. But now, the Serpent Crown has given Namor telepathic abilities on par with psychic powerhouses like Professor X. Namor will be able to suss out the Avengers' next moves and keep his bloodthirsty kingdom 10 steps ahead of their enemies, if he can keep his sanity.