Tony Stark is no stranger to upgrading his arsenal. Iron Man knows that science and technology are his best friends, but what happens when they're no use against an enemy? While Stark often avoids magic as much as possible, he was forced to incorporate it into his suit to stop yet another Doctor Doom plot.
Iron Man: Legacy of Doom by David Michelinie, Bob Layton, Ron Lim and Moose Baumann opens with Tony Stark disposing of his now-defunct Mark VIII armor. While analyzing the suit in that 2008 story, Stark discovers a lost memory recorded by the suit that he has no recollection of. While Iron Man is working on a Stark satellite, Doctor Doom approaches him and demanded his help. Stark flies to Doom's Castle in Latveria, which is currently undergoing a siege by the Latverian military. Stark then intervened and destroyed the military vehicles to keep Doom from harming the citizens. With the military maintained, Doom and Stark travel to the depths of hell in order to find Mephisto.
Mephisto rewards Doom with a metal shard before the cloaked villain vanishes. Mephisto then tells Stark that he made a deal with Doom to bring Iron Man to the demon. Mephisto puts Iron Man's will to the test, unleashing denizens of demons upon the armored suit. Among these demons is an armored demonic version of Tony's father. After Stark defeats his demonic dad, he is able to connect the armor the demon is wearing to the faulty travel chip that Doom left. This returns Iron Man to Doom's castle where the villain is wearing a sleek new black robe and holding the powerful sword Excalibur.
While Stark fought through hell, Doom was able to trap Morgan Le Fay, King Arthur's half-sister. Doom declares that the ritual needed to activate Excalibur needed to be performed by somebody who shares Arthur's blood. The ritual bonds the sword to Doom's suit. Doom, no longer needing Morgan, sends her back to her own time period. As Tony returns to Latveria, he strikes out at Doom. Excalibur has made Victor invincible, which he demonstrates by swinging the sword right through Iron Man's armor. Seeing his unstoppable power. Iron Man flees the scene.
Stark lands in a field to recharge his armor where he is met by a hologram of Merlin. Tony and Doom both met Merlin back in 1989's Iron Man #250, by Michelinie and Layton, but that memory was also erased from the pair's minds by Merlin. The wizard explains to Tony that he needs to get the scabbard for Excalibur. While the sword grants invincibility, the scabbard grants invulnerability, so Tony races to a Stonehenge-like area in Scotland when he runs into Doom. However, Tony is able to decode the scabbard riddle while fending off Doom and retrieves the scabbard. Unfortunately, a gigantic eyeball appears from the sky. Tony merges with the scabbard, creating a new set of armor that resembles a knight's suit.
Doom tells Iron Man that he angered this monster by trying to steal a book from it to increase his arcane knowledge. In response, the creature swore to destroy all that Doom possessed. The sword and the scabbard are useless when used separately against the monster. Merlin appears to the duo and encourages them to combine the pieces of the historic artifact. The problem is that the scabbard does not technically exist anymore. Tony's Iron Man suit became the scabbard. Doom then impales Iron Man in the chest, which liquefies the creature. The pair return to their original costumes and Merlin erases their memories once again. Merlin then takes the two pieces of Excalibur to the Lady of the Lake to guard the weapon.
The flashback ends and Tony is seen standing in his lab after being flooded with memories. Tony then buys the property that the lake holding Excalibur is located on. He decides to build a mall over top of the lake, forever sealing the weapon away and sending a message to Merlin in the process.
Iron Man has fought all kinds of magical villains in his heyday, but it's not often that he finds himself in possession of the arcane arts. While Doom and Tony were able to cooperate and defeat the monster, it's best not to plan for these overpowered supers to team up again.