Mist is an ability that has been described by those even among Hemlock's peers as being "blatanly overpowered" and "nearly broken" in strength. While not overtly an offensive power, it does grant him almost total defense from direct damage, the ability to interfere with the minds of those trapped within it, and deal great damage without having to lift a finger. Often, Hemlock will combine this ability with his already impressive grasp of magic in order to defeat his targets rather than facing them directly, concealed safely within his Mist. Because of this, the man is not exaggerating when he states that he is one of the strongest of the Black Knights, if only because of how difficult it is to land a blow on him in the first place, and to fight him in general.
The power takes the form of an eponymous mist that is constantly generated and hangs around his person (though in meetings with fellow Knights and those he does not wish to overly anger he has shown the ability to keep it dissipated). While at full strength it fully wraps around and encompasses his immediate surroundings and beyond, in base form it simply appears to be a vague black fog hanging around his person. It can expand and shrink with incredible speed, often without people catching it in the act and it appearing to have simply changed shape. Hemlock appears to need no commands for it to expand or shrink, with Mist following his will as an absolute. Often, he will combine this with his illusion-based magic and have the mist appear before he reveals himself, seemingly being "born" from the mist and increasing the drama in his various debuts. Often, it is a sign of his presence, as it can be found (if only in vague tatters) before one comes across Hemlock himself. When trapped inside, Mist takes the form of an impenetrable fog that confounds and limits the senses. It is largely a dark, dark grey, with the occasional massive stretch of black floating around, and those within it have reported that their senses grow dim, inhibiting their reaction time. While the fog appears to be natural, Mist is in fact made out of Hemlock's magical energy and it is saturated to the brim with the stuff.
The true danger of Mist, however, lies not within simply being trapped in it, but rather what can happen while one is inside. Hemlock can freely manipulate his own position within the fog, fazing in and out of view and in different locations every time, appearing to warp with ease. He also wields power of a "smoke and mirrors" effect that allows him to create multiple copies of himself, all of them appearing to be him and carrying the same weight until struck (leading to them feeling light and dissipating). Additional illusions can be created, though these rarely appear unless he knows his opponent intimately enough to have knowledge of their greatest fears or weaknesses. This makes Hemlock an extraordinarily difficult opponent to hit, as his illusion capabilities combine with the inhibited senses of his target. Even if one can fire off a blow, Mist disperses most attacks across its expanse, preventing any damage from hitting its user, and often hitting the attacker and their comrades. Hemlock, shielded by the cloud, can also use his own knowledge of magic to launch attackers upon his enemy while they are disoriented by the effects of Mist. Finally, in order to replenish his own magical energy to his heart's content, those who have been surrounded by the power are slowly drained of their own magical energy, it being added to his reserve. Thus, they are also gradually weakened passively as well as offensively.
Yet, even this is not the greatest danger of being devoured by Mist. As it is made out of Hemlock's magical energy, it permeates everything within it. The cloud can enter the bodies of his targets, usually through openings such as ears, mouths, eyes, and even skin pores in some cases, allowing the Black Knight access to their own abilities. From here, he can "jack" into their power(s) and magic, interfering and distorting it to a point where at times it is rendered almost useless, or appropriating it for his own use if not outright disabling it. He can also influence his opponent's body to some extent, though the range of this manipulation expands the weaker and more disoriented the target becomes, with those who have broken down totally under Mist being susceptible to his complete control both mentally and physically. As those with weaker Power Levels and constitutions fall the fastest, it is not unknown for Hemlock to take a great deal of ordinary knights and even civilian as his puppets, keeping a small amount of the mist within their bodies even after they have left and maintaining his control over them, so that they may rush to his aid in a tight spot, or serve as convenient meat shields. Throughout all this, they will often act their normal selves until the Mist within them is activated. He has also shown the ability, through limited physical manipulation, to weaken and rob his opponents of their skills. Due to this, on occasion Hemlock has been able to physically beat down opponents who would normally surpass him in that field.
Hemlock appears to be fond of his ability, often talking to it as if it was an actual person rather than a Power.