This villain is almost a guaranteed mass-casualty event if he gets into a populated area, so don't let that happen if you can. If he's feeling mean he might decide to take hostages to toy with, although there's not much he wants that the world can give him.
Samuel Hakes, The Black Miasma
Samuel Hakes (Prisoner #761-176) was facing a life sentence in prison without parole after being found guilty of multiple spree murders, so volunteering to participate in a research trial for better living conditions seemed like a risk worth taking. Besides, everyone had heard rumors of another con who'd been granted superhuman strength and durability in a similar experiment. Maybe Hakes would get lucky too.
Instead, he was exposed to an exotic chemical that led to an irreversible physical transformation, robbing him of his humanity and part of his sanity but also allowing him to escape and resume his killing spree. The authorities dubbed his new form the Black Miasma - a reasonable description of his new form - and were forced to call in multiple heroes to finally contain him in an airtight portable cell. Several of them died in the process, giving Hakes a reputation as a hero-killer as well as a mass murderer.
Despite being moved to a max-security super-prison the Black Miasma has escaped several times since then, albeit always for brief periods. He's even been set free by other villains on occasion, either as a deliberate distraction or in hopes of making an alliance with him for some scheme. A few have even succeeded in convincing him to cooperate, although others have perished in his deadly haze for their trouble. While he's largely motivated by murderous rage and hatred toward everyone who still has a physical body, he'd be quick to listen to any plausible offer to assist him in regaining his original form. He doesn't want to give up his powers in the process, but being able to transform at will would be ideal for him.
Description: A shifting, formless cloud of dark particles. In its base state it appears to be a sooty haze about fifty feet in diameter (large enough to envelope or fill many buildings) that flows from place to place of its own volition. At maximum compression it can squeeze itself down to a globular mass about eight feet in diameter with a consistency akin to thick, black bank of smoke, or it can disperse to a maximum diameter of just over one hundred feet. It can vary its density independent of its total volume, ranging from an almost invisible dark mist to a slimy mass of fog slightly thinner than water. The being can adopt more structured forms to flow through openings or passages, or throw out pseudopods to pursue a fleeing foe, but a humanoid form is beyond it, only fragments of one like a huge menacing face or a single reaching hand. Its voice seems to come from nowhere and sounds like a susurrus of falling ash.
Gender: Moved Past It Age: 31 Volume: Variable, Base Diameter ~50' Eyes: None
Hair: None Skin: None Build: Amorphous Cloud
Approach: Relentless
Archetype: Titan (Status Challenge: Analyze Cloud Structure 00 Locate Prime Nexus 0)
Health: 50 + (5 x H)
Powers: Density Control d10, Size-Changing d8, Intangibility d6
Qualities: Close Combat d10, Convict Test Subject d8, Stealth d8, Fitness d6
Status: Titan Challenge Start - d12 / Stage 1 Completed - d10 / Stage 2 Completed - d8
Abilities:
Amorphous Form (I) Reduce all damage you take by 6 (at d12 status), 4 (at d10 status), or 2 (at d8 or less status).
Deadly Miasma (A) Attack multiple targets using Density Control. Hinder those targets using your Min die.
Focused Hate (A) Attack using Close Combat. Use your Max die. If the target does not Attack you on their next turn, Hinder them using your Mid die.
Roiling Vapor (R) When Attacked by a roll that includes doubles, remove one success from the Titan's challenge.
Vindictive Pursuit (R) When an opponent moves away from you, you may follow them and Hinder them by rolling your single status die.
Upgrades & Masteries (optional):
Power Upgrade (I) +20 Health. Increase all Power dice sizes by one (max d12).
Master of Annihilation (I) If you can cause massive collateral damage without regard for casualties, automatically succeed at an Overcome in a situation where a show of overwhelming force would help.
Tactics
The Black Miasma is a murderous but straightforward opponent, often concentrating more on inflicting mass casualties to innocents and mundane law enforcement than defeating the heroes. His go-to ability when there are victims within the cloud that makes up his being is Deadly Miasma, otherwise he's quick to resort to Overcomes with creative power uses to get at targets cowering from him in supposed safety. His Amorphous Form lets him shrug off a lot of damage, and Roiling Vapor helps keep his defenses at peak. If a single hero manages to get his attention (often by applying penalties to him, which hurt his offense and Overcomes a lot) he'll use Focused Hate for payback. Targets fleeing from him will also draw a Vindictive Pursuit reaction, which is his primary mobility trick.
His upgrade makes him much more durable and reflects him adapting to his transformation over time. His mastery leans hard into his homicidal nature and cruelty.
Trivia
The Black Miasma's combination of powers and Titan archetype reflect his status as a gigantic ever-shifting cloud of dark mist. While not quite fully insubstantial, he can seep through anything short of an air-tight barrier in short order, as well as varying his opacity and overall shape considerably. His version of Density Control not only affects him, when in contact with solid matter he can slowly penetrate its substance and break it down on a molecular level, effectively disintegrating objects and people. The process is swifter with organic matter, but even metals and ceramics can gradually be worn down and even a pinhole breach will let him slip through a formerly impenetrable barrier.
He's also remarkably hard to damage due to his makeup and considerable size, although his consciousness is somewhat concentrated in a smaller prime nexus which offers a weak point if it can be located. Black Miasma's principle limitation is his lack of mobility. While able to flow about at will even in face of fairly strong winds (anything less than hurricane force) he does so at roughly walking pace and can't actually fly or swim as such. He can "climb" a building or "walk" across the surface of water, and dropping off a height in low-density form won't hurt him at all, but even a civilian can escape him for a while by running fast enough.
How his senses function is unclear, but he's known to be able to see, hear and feel everything within the confines of his volume, as well as perceiving nearby areas about as well as a mundane human could. He has to concentrate on a smaller area to really notice details (like the identity of who's moving within him) but has a general sense of what's going on near or inside him.
Meta-textually, Samuel Hakes is (or was, depending on how you look at it) an African-American and "the Black Miasma" is a nod to often-problematic naming practices in comics. He despises his supranym and using his real name might get you a break when talking to him, or it might enrage him as a reminder of his past depending on his mood.