WARNING: The following contains spoilers for Symbiote Spider-Man: King in Black #2 by Peter David, Greg Land, Jay Leisten, Frank D'Armata and VC's Joe Sabino, on sale now.
In the "King in Black" event, Knull has finally arrived on Earth, and he has taken over the entire planet in record time. But the present isn't the only era where the dark god of the symbiotes' presence can be felt. In Symbiote Spider-Man: King in Black #1, which takes place shortly after the 1984-1985 event series Secret Wars, Knull's attack proves to have an effect on the past. Here, one of his dark creations, a shadow creature known as Mister E, took over the Ravencroft Institute in the name of his master.
Now, in the second issue of the series, Mister E continues his attack in the past -- and it's while facing the Black Knight that the shadow creature confirms the Ebony Blade is one weapon that could kill Knull.
In Symbiote Spider-Man: King in Black #1, a black suit-wearing Spider-Man arrived at the Ravencroft Institute to find that it had been taken over by Mister E, who had transformed everyone in the facility into a shadow creature like himself. The superhero took on the monster but thankfully, he didn't have to face him alone: the Black Knight arrived atop his winged horse, and his magical sword, the Ebony Blade, proved to have a devastating effect on Mister E.
Wounded, the creature left the battle -- and now, in issue #2, Spider-Man and Black Knight set out to find him again. During their chase however, the two end up having to split up: Spider-Man has to save J. Jonah Jameson at the Daily Bugle, which is under attack from a shadow creature. As for the Black Knight, he is called back to Avengers Mansion by the wizard Merlin.
While at the Avengers headquarters, the Black Knight confers with Merlin, who reveals himself to actually be Mister E. The shadow creature simply took on the form of the wizard to lure the Black Knight into a trap.
The villain is after the Black Knight's signature weapon, the Ebony Blade. The sword is a magical artifact crafted by Merlin. Its properties allow it to cut through anything, and it is impervious to other magical attacks. In Symbiote Spider-Man: King in Black #1, we saw that the blade was able to wound Mister E, one of Knull's creations. This indicated that perhaps the weapon could have an effect on the god of the symbiotes himself -- something which Mister E now confirms in this issue.
The shadow creature reveals that Knull is vulnerable to the Ebony Blade and that, if given the right power upgrade, it could potentially kill the cosmic villain. Mister E then takes the sword for himself, and stabs the Black Knight with it before disappearing, claiming he has very special plans for the magical sword.
Now, we know that Mister E is in the service of Knull in the past, which means it's possible his mission is to either hide the blade forever, or destroy it if he can. But despite that, although he might be badly wounded, the Black Knight is now the only person in the Marvel Universe who knows Knull's weakness. All he would need is to communicate this message from the past to the present somehow, or to get his sword back and join the battle.
Luckily, the time-traveling Kang arrives at the end of the issue to rescue the Black Knight -- and with the Avengers villain taking part in the same fight against Knull, he could help the Black Knight relay what he knows across time: how to stop Knull, once and for all.