Bankai Special Ability: Tensa Zangetsu, much like its Shikai form, is used heavily for melee combat, but also possess a certain special ability.
Hyper-Speed Combat: Ichigo takes all the power of his Bankai and compresses it into a small, condensed form. Then, he uses the power of the Bankai to perform high-speed combat. His new speed is so great, that it also enhances his Flash Step prowess and allows him to create dozens of afterimages to confuse his opponent.
Enhanced Strength: Ichigo's Bankai also allows him to further enhance his natural great strength as shown from how effortlessly he blocked a punch from Yammy Llargo, an Espada known primarily for his immense strength. He is strong enough to cut through Yammy's Hierro with relative ease. The sudden boost in strength upon releasing allows Ichigo to break free from any attack that binds him and prevents him from moving. After his training in the Dangai, Ichigo's strength has drastically increased to the point where a single swing of his sword can level a mountain. He can grab hold of Aizen's Zanpakutō blade with his bare hand without feeling any of the exerted force, although that force was capable of doing considerable damage to the surrounding area. He is able to effortlessly break through a #90. Hadō spell "Kurohitsugi" with his bare hand alone.
Enhanced Getsuga Tenshō: Tensa Zangetsu retains the use of Getsuga Tenshō and can be used in the same manners, but can be used in an enhanced form. When used in Bankai, these potent blasts are black with a red outline and their path can be controlled, with explosively augmented power and speed. During Byakuya Kuchiki's fight with Ichigo, he refers to this attack as a "Kuroi Getsuga" (黒月牙, "Black Moon Fang"), referring to the attack's darkened color. Ichigo has stated that the Black Getsuga was originally Hollow Ichigo's technique, and has been proven as Ichigo had no knowledge of it during his fight with Byakuya Kuchiki, using the original Getsuga when in Bankai, and Hollow Ichigo stated that all Ichigo was doing when he used the technique was copying his inner Hollow. Ichigo can also keep Getsuga Tenshō within Tensa Zangetsu to augment his sword swings.
Enhanced Spiritual Power: His reiatsu is so intense and rough as well as thick and heavy that it can suffocate Humans just by being in the general vicinity of his released Bankai. Ichigo's reiatsu was solid in his Bankai despite him only recently acquiring it. In addition, his already immense spiritual energy has grandly and explosively increased, and now has a deep black spiritual energy with a crimson outline. It has come to a point where the red-outlined black energy emanates off of Ichigo's body when his spiritual pressure is exerted, replacing his blue aura. Ever since Ichigo defeated his inner Hollow and affirming his place as a Visored, he produces a black aura with a red outline that surrounds him as he initiates Bankai, rather than a white aura that shoots high into the sky. After his training in the Dangai, Ichigo's ability to sense reiatsu has increased greatly as he can now sense his sisters blocks away through various buildings and determine their current status. According to Sōsuke Aizen, by achieving evolution into a dimension separate from Shinigami, both Shinigami and Humans have become unable to feel his reiatsu unless he voluntarily lowers his level and allows them to interfere, in the same way that a two-dimensional being is unable to interfere with a three-dimensional being. In this same way, he surmises that Ichigo is standing in a dimension even higher than the one he is in.
Enhanced Bankai Duration: Furthermore, the fact that all of his energy is "compressed" means that usage of his Bankai doesn't expel as much spiritual power as other Bankai from the point of activation, thus allowing him to use Tensa Zangetsu at a much longer duration than any other Bankai users of his level. From his final encounter with Grimmjow in Hueco Mundo till Aizen's defeat, Ichigo was about three months in Bankai state continuously.
Saigo no Getsuga Tenshō (最後の月牙天衝, The Final Moon Fang Heaven-Piercer): By using this technique, Ichigo becomes the Getsuga (月牙, Moon Fang) itself. It is referred to as the “Final” Getsuga Tenshō because if Ichigo uses it, he loses all of his Shinigami powers. For the duration of the ability, Ichigo’s hair turns black, and becomes waist-length. Light bluish-gray bandages form around his body, tightly wrapped around his torso, right arm, and face, ending just beneath his eyes. Black flame-like markings spread across his chest and wrap around his left arm, and the remains of a tattered black cloak cover his lower body. In this form, Ichigo’s body constantly emits smoky black reiatsu, most of which is focused around his right arm. Being in this form allows Ichigo to use Mugetsu. Once it is used, the transformation dissipates, in which he will then lose consciousness accompanied by intense pain with the loss of his Shinigami powers following. Then, any remaining reiatsu stabilizes and he will awaken (sometime later, roughly a month) followed shortly by the loss of his remaining Reiryoku.
Mugetsu (無月, Moonless Sky): Ichigo generates a blade of deep black spiritual energy in his hand and swings it towards the target. Doing so causes a massive veil of black spiritual energy to erupt upwards and approach the target, darkening the sky, and heavily damaging anything caught within the blast. The energy then continues to rise, dissipating into the sky.