Michelangelo said he was simply freeing his sculptures from the marble that they were trapped in. I can almost feel the mysterium slithering across the air...and into my mind. It wants to be free. So it shall be. 
Appearing in "If I Only Had a Heart"
Featured Characters:
Supporting Characters:
Antagonists:
- Orchis
- Stark Sentinels (Destruction)
- Nimrod
Other Characters:
- Stark Enterprises (Mentioned in narration)
- Blind Melon (Mentioned)
- Warden Drummond
- Sandman (Flint Marko)
- Arthur Parks
- Jen Walters (Mentioned in narration)
- Avengers (Mentioned)
- Michelangelo (Mentioned)
Races and Species:
Locations:
Items:
- Pym Particles
- War Machine Armor Model 1
- Iron Man Armor Model 72 (Mysterium Armor)
- Mysterium (In the Mysterium and Sentinel Buster Armor)
- Iron Man Armor Model 73 (Sentinel Buster Armor)
- Magneto's Helmet
- Terrigen Mist
Synopsis for "If I Only Had a Heart"
In his cell at the Polunsky Unit in Texas, Jim Rhodes is approached by two Orchis agents around the time Iron Man was unveiling the Sentinel Buster Armor. He presses on his pendant, expanding the miniaturized War Machine Armor embedded in it to full size. Using the armor for cover, he suits up and escapes his cell, incapacitating the agents. Warden Drummond rushes in, but trips over an unconscious agent. War Machine grabs Drummond, tearing his clothes to embarrass him, and then flies out, hauling a police car carrying Sandman and Arthur Parks. He sends Tony an audio message for a rendezvous.
Aboard the felled Sentinel Buster Armor in the Australian outback, Iron Man debriefs Magneto and introduces him to Feilong. The trio sets out to destroy the secret Stark Sentinel factories run by Nimrod still producing these killer robots. Feilong accounts for the factories' location, since he retained them due to his photographic memory, and Magneto for the Sentinel Buster's power source. As such, the Sentinel Buster rises up again. Stark tries to playfully rally his allies with the Avengers's battelcry, but he is shot down in unison. They first destroy a factory in New South Wales, then a facility in Tokyo, effortlessly eliminating the Stark Sentinels guarding it.
Suddenly, Nimrod knocks down the Stark Sentinel, which crashes onto a railroad just as a train approaches. Iron Man exits the giant suit to bridge the broken tracks with his body, leaving Magneto and Feilong to start the fight ahead. After Nimrod resists Feilong's concussive blast, Magneto detaches the Sentinel Buster's head and bends it around the robot. Nimrod reaches out to Magneto and sprays him with Terrigen Mists, but Iron Man sweeps in and blasts nitrogen at the small billow, condensing it into a harmless puddle. Nimrod breaks free, but Magneto manipulates the mysterium scraps surrounding him, noting that it feels almost alive. He turns them into a spear and impales Nimrod. Taking advantage of the mysterium's hyper-conductivity, Tony grasps the spear and fires a powerful electric discharge, but Nimrod remains standing. Magneto transforms more mysterium into sharp tendrils, burrowing it into and throughout Nimrod's body. As his body shuts down, Nimrod boasts that he exists in other bodies. Magneto notes the mysterium's structure has changed, as if it had died when in contact with Nimrod. The Master of Magnetism leaves to fight Nimrod's other bodies, leaving Feilong restrained, and wishes Tony luck. Feilong coyly asks what is next, and Stark knocks him out with a punch, declaring he will now pay for his crimes.
Solicit Synopsis
SIDE BY SIDE WITH…MAGNETO!
• For years, the Master of Magnetism was Iron Man’s greatest fear.
• But to take down Orchis, will Tony have to work with the X-Men’s former adversary?
• And will a fight against every Sentinel on Earth be too much for even these two powerhouses?Notes
- As Jim Rhodes deploys his clandestine War Machine Armor, Tony Stark's narration comments on him geting hold of some Pym Particles and sending it to Rhodey. This happened in issue #12.
- Feilong accuses Magneto of stealing Mars from him. He is referring to mutantkind's terraformation, colonization rechristening of Mars as "Arakko," which happened in Planet-Size X-Men #1. Feilong's biggest source of scorn toward mutantkind comes from that, as established in X-Men (Vol. 6) #1.
- When Magneto notices that Tony is injured and he jokes that he cut himself shaving, an editor's note cites issue #15, when Tony was gashed by a Sentinel Zero at the Hellfire Club.
- Feilong attributes his retaining of the location of the Stark Sentinel to his photographic memory. This attribute of Feilong was first established in issue #5.
- Nimrod attacks Magneto with Terrigen Mists because the have adverse effects in mutant physiology. This was first established in Avengers (Vol. 6) #0, with the Terrigen Mist's ability to induce "M-Pox" being a prevalent plot point throughout Marvel comics in 2015–2017 as a Terrigen Cloud roamed the Earth after being released into the atmosphere in Infinity #3. However, as per Death of X #2, it is this specific Terrigen Mist that is harmful to mutants due to its molecular composition changing after being mixed with the atmosphere, and not pure Terrigen.
- When Magneto leaves to fight Nimrod's other bodies, an editor's note directs readers to Fall of the House of X #5.
Trivia
- The title of this issue's story is taken from the song "If I Only Had a Heart" from the 1939 film The Wizard of Oz.
- While taking down the Orchis agents sent to kill him, War Machine threatens Feilong, he boasts that he is "gonna kick this vintage armor's boot so far up his ass--that he's gonna taste Blind Melon." Blind Melon is an American alternative rock band most active in the 1990s.
- In his narration, Tony Stark describes Tokyo as "the land of the giant robot," alluding to the mecha genre proliferated in Japan.
- When bending mysterium to finish off Nimrod, Magneto paraphrases and attributes to Italian sculptor Michelangelo a sentiment widely credited to him, that he claimed "he was simply freeing his sculptures from the marble that they were trapped in," as it is put in this issue's dialogue.