In Marvel’s latest TV show, Luke Cage
was able to be shot by the new Judas bullet.
In the comics or other media, are there other things that have been shown to be able to harm Luke?
In the comics, Luke is not invulnerable to damage, he's just extremely resistant. His skin and bones are more dense than most conventional metals, so normal gunfire and weapons just bounce off. (I believe it's usually classified as being stronger than titanium, though that might be understating it.)
Even with this extreme resistance to injury, Cage still has a few weak spots, though:
Natural openings in his skin. While his skin is bulletproof, and his bones are dense, his internal organs appear to be more vulnerable. So, an attack that can bypass his skin completely would be dangerous. For example, being shot down his throat would likely damage his heart and lungs. In Jessica Jones, Claire is able to drain excess spinal fluid from Cage by going through the back of his eye.
Very sharp/hot things. His skin can be cut by something strong enough to slice through or otherwise break dense metals. Adamantium weapons will cut him, as would a high-powered laser. I believe there has been at least one case where such a laser was used to perform surgery on him, and he's been caught in laser traps as well:
Extreme physical force. A sufficiently strong punch from someone like Hulk or Iron Fist could also break his bones and cause some serious damage:
Non-physical damage. In addition to his damage resistant skin, he also has an accelerated healing factor. However, it can be overwhelmed by things like poison and radiation, in sufficiently high doses. For example, in Age of Ultron #4 he is killed by nuclear radiation from Ultron's sentinels. He can also die from drowning, suffocation, and other things that don't do any physical damage to him.
Internal injuries. Even though his skin is "unbreakable", the wrong kind of impact could cause internal injuries. The fact that he can't be treated at a normal medical facility (since they can't operate on him with expensive medical lasers) would turn into a hindrance. We've seen two examples of this in the MCU: in Jessica Jones, a point-blank shotgun blast to his head causes hemorrhaging in his brain but they can't do a spinal tap to relieve it; and when shrapnel manages to get into his body and start damaging his organs, it can't be removed because his skin breaks the scalpels.
Luke Cage's powers on Earth-616
Luke's serum and physical immersion process was designed to boost regenerative capacity in soldiers. Due to the tampering by officer Rackham, Cage was overexposed and instead of dying as a result the treatment gave him several superhuman capacities.
Increased density: His muscle and bone density were increased to nearly 2.5 times the Human norm with a corresponding increase in weight. He is six feet, six inches tall, weighing 425 pounds.
Superhuman strength: The treatment increased his strength significantly allowing him to lift effectively about 25 tons (though he has lifted more when under extreme stress). This is sufficient strength to lift an armored personnel carrier over his head or throw a conventional car about 25 yards.
Tougher than Steel: In addition to his increased molecular density, his dermal layers and underlying tissues have become super-humanly durable, with a corresponding increase in his pain threshold while having the equivalent durability of the hardest conventional metals known: Titanium steel. His skin can resist high-caliber bullets, puncture or penetration wounds, (steel weapons shatter on impact), explosives, corrosives, and extremes in pressure and temperature without sustaining damage. A later exposure to said experiments further enhanced his strength and durability.
Superhuman stamina and recovery: In addition to his other superhuman attributes, he has a faster-than-normal recovery time from injury. Not quite a healing factor, Cage recovers from trauma at three times the normal rate. Which can be handy, since conventional surgery is all but impossible with his hardened skin and dense organs. A high-energy laser can do the job if necessary. He also has an incredible level of stamina, producing almost no fatigue-poisons making him capable of using his abilities full out for twenty-four hours.
Strangely enough, despite his superhuman durability, Luke is still fundamentally human. Anything capable of killing a normal human can, with sufficient magnitude, injure or even kill Cage.
Essentially Human: Despite his perfect cellular regeneration (which hints at a form of immortality or at least reduced aging) Cage still appears to need to breathe, eat and drink and excrete normally. He may be able to go for longer periods than a normal Human without food, water or air, but without them, he will eventually die.
Brute Force: While Cage has mixed it up with some of the strongest heroes in the Marvel Universe, he has learned there are limits to how much damage even his nigh-invulnerable form can withstand. He can be stunned if he received too much damage to his brain, though his recovery rate allows him to repair any damage that isn't instantly fatal. His eyes, nose and mouth are vulnerable to attacks. While they are stronger and denser than normal Human eyes, Luke has been known to shield his face indicating a degree of vulnerability there.
Lasers with sufficient power have been known to be able to penetrate his skin. Which can be an asset if he needs surgery since conventional metal surgical tools cannot. While this was true before Cage received a second augmentation, it appears a laser would need to be significantly more powerful than what was once needed. In a battle against an augmented Living Laser, Cage was mostly unaffected by his powers.
Hard exterior, chewier center: While Luke's exterior is extremely resilient, his inner body, his eyes, his mucus membranes are far less durable than his exterior. He may be able to withstand and recover from chemical attacks like mace, he can be affected by them, if he is caught off-guard.
Most of the abilities Cage possesses in the comics are transferred over, at a reduced capacity. He still has superhuman durability, enhanced strength, and an increased recovery rate.
While normal bullets still won't penetrate his skin, it does appear if he is struck by a powerful weapon at short range he can suffer brain injuries if he is struck in the head. During the Jessica Jones series, after taking a shotgun blast at point blank range, Cage suffered a brain injury requiring medical attention. To reduce cranial pressure he has to have spinal fluid drained through his sinus cavity behind his eye.
The Judas Bullet, an alien-derived technology appeared to be able to strike, and enter his body. My suspicion is the bullet uses Antarctic vibranium to destabilize his body's metallic-like resilience and penetrate his body. This is, as yet unconfirmed in the MCU, but such materials do exist in the canon comic Universe. There was also an artificial version of vibranium with similar explosive capacities called Reverbium.
There is also speculation of the material being used for the Judas Bullets being derived from the remnants of the Chitauri Event from the Avengers. Given the Chitauri have a level of technology beyond that which can be found on Earth, it is conceivable these bullets could be derived from such technology.
Considering the special effects of the bullets, I would be inclined to believe they are derived from alien, possibly Chitauri technology and changed to work with Human weaponry. But they would need to be CREATED with the same technology since most normal Human technologies should activate the material's features during the manufacturing process; this implies there is potentially an arms dealer in possession of alien technology or an alien weapons manufacturer on Earth.
We're all missing one seriously glaring weakness here. The man has to breathe. Any kind of poison gas would easily kill him. He could probably be drowned too, as we see in Season 1 of Luke Cage when he needs a breathing mask while being healed in the acid bath.