Warning: Spoilers for Fantastic Four #28

Fantastic Four just discovered. Try as they might, the of the Fantastic Four have never vanquished the threat of Doom for good, and they've now found a weapon that can succeed where they have failed over the years. However, Doctor Doom isn't one to go down without a fight, even against his version of Kryptonite.

In Fantastic Four #28 by Ryan North, Steven Cummings, Wayne Faucher, Jesus Aburtov, and Joe Caramagna, Reed Richards reacts to Doctor Doom becoming the Marvel Universe's top villain by studying magic. To aid him in this endeavor, he and the Invisible Woman travel through time with the Black Knight to locate a Fated Sword with magical properties.

In the end, Victor von Doom appears to reveal that he tricked them into uncovering the sword's location. The sword turns out to not be the "Fated Sword" and is instead the Doomblade, Doctor Doom's ultimate weakness in Marvel lore.

The Doomblade: Doctor Doom Reveals the Only Weapon That Can Damage Him

Doom May Be Powerful, But Even He Is Vulnerable to This Ancient Sword

The sword the Fantastic Four find is known as the Doomblade, and according to Doom, it is "the one magical weapon that could hurt me". Created in the 1300s, the location of this artifact has long been a mystery even to Doom, hence why he goes undercover to enlist the Fantastic Four's help. Manipulating Reed Richards' genius to carry out his wicked deeds, Doom procures the weapon and proceeds to destroy it so that it cannot be used against him. Reed and Sue's blunder inadvertently strips Marvel's superheroes of a surefire method to eliminate Doctor Doom, granting him a clear path to power.

Doctor Doom is stronger than he's ever been before, making the Doomblade the only possible way for Marvel's heroes to strike him down before he can enact his plot. He ascended to the role of One World Under Doom event rapidly approaching, the Fantastic Four are desperate to stop Doom before it's too late. Unfortunately, the Doomblade's destruction has sealed the Marvel Universe's fate.

Without the Doomblade, Doctor Doom Has Officially Become Unstoppable

The Fantastic Four Is Powerless Against Sorcerer Supreme Doom

Now that Doctor Doom has eradicated the Doomblade, the Fantastic Four's heroes have squandered their best chance at thwarting his plans. The tiny modicum of most powerful Sorcerer Supreme to date, and now he's virtually unstoppable. The Fantastic Four will need to find a new plan to take down Doctor Doom, since the only weapon that can kill him is not an option.

Fantastic Four #28 is available now from Marvel Comics.