In a hidden Inhuman city, Thane was known as The Healer, and used his powers to help the sick and poorly. Thane's true nature was revealed when Black Bolt activated the Terrigen Bomb during his fight with Thanos, leading to wide-spread mutations across Earth. As this happened however, his people were killed in the process due to his powers activating uncontrollably.
Thane was created by Jonathan Hickman and Mike Deodato Jr. in New Avengers #10, as part of the Infinity crossover event.
Major Story Arcs
After his powers were awakened by the Terrigen Bomb, Thane, who had spent his life healing others, looked in horror as his new power had killed all he knew. He was found by Ebony Maw, who quickly manipulated and trapped Thane, who is the last remaining offspring of Thanos. Maw gave Thane a suit that allowed him to control his abilities.
As Thanos was finally going to kill his last child, the Avengers arrived on the scene. Ebony Maw continued to talk to Thane about his power and destiny. He released Thane to see if he would save the world, in doing so become his father's son and take life. Thane accepted and put Thanos in a state of 'living death.'
The Black Vortex
He left the Earth with Ebony Maw, still under his manipulation. He had moved to a distant planet and gathered a small but dedicated cult built around his reputation as a healer and destroyer, as well as the son of Thanos. A space gangster known as "Mister Knife" tried to convince Thane to join his scheme to gain the use of a object known as the Black Vortex, a mysterious object that granted great power to those who used it. Thane refused at first (why would the son of Thanos need more power anyway?) but after his cult was all killed in a attack, Knife pointed the blame at the X-Men and Avengers for the massacre. Enraged, Thane promised to assist Knife as long as he gained access to the Vortex so that he may crush those who caused the killings.
With the assistance of Thane, Knife had access to the Vortex, and willingly gave his will to it in return for far greater strength. As apart of the deal with Knife, he used his newly enhanced powers to cover a entire planet in amber, imprisoning everyone on it. After trying to fight off Captain Marvel, Thane was sent flying from the planet he was on by Gara, appointed protector of the Vortex.
Considering that the powers that the Black Vortex gives slowly wear off over time, it can be presumed that Thane eventually lost whatever new power he gained from the device.
Encouraged by the words of Maw, Thane attempts to take over the territory of the Black Quadrant, a old base for Thanos and his army, now occupied by Corvus Grave. However, Grave had allied himself with the Astral Coven, extremely powerful witches on par with Death herself. Hopelessly outmatched, Thane was completely wiped out by the trio, and was later imprisoned by Grave in his own cell.
Breaking out after three months, Thane puts together a team consisting of Champion, Starfox and Nebula with the mission of killing a already dying Thanos (as he had found out that his unique mutated genes, the ones that gave him his unusual appearance and strength were also degenerating and killing him). After fighting through Terrax's ship as well as himself, It is later revealed he just used them to obtain the Phoenix Force and was working with Death (who had freed him from his cell in the first place) to take his father's throne back.
Nebula, enraged with Thane and understanding of the capabilities of what he could do with the Phoenix kills him. This, however, accidentally makes him comparable with the Force, and he becomes a host of it, escaping.
With the Force in his control and the assistance of Death, Thane easily beats up and humiliates Thanos, who by this point was struggling to move around, let alone fight him. Thane left his father to die a slow and painful death due to the virus rather than killing him. Death by this point was using Thane's new found powers to kill masses of people, even entire planets. However, Thane's paranoia over his father still alive made him go back to Titan to try and finish him off: but he had been gone by then, having convinced Thane's team that he was too much of a threat to continue to exist, as the Phoenix Force had the potential to destroy the entire universe in the wrong hands.
Thane eventually caught up with Champion and Nebula after they tried to distract him from Thanos, who was currently at the God Quarry in a attempt to regain his missing strength. Thane smashed around the pair as they tried in vain to handle him until Thanos returned from the Quarry with all of his power back to him. Father and son brawled with each other- so violently so that they cracked and destroyed a planet with their attacks, and Thanos dragged Thane into the God Quarry, as his real plan was to take him to a place where the Phoenix Force had no effect, the Quarry being one of them, as the Astral Coven removed Thane's Phoenix powers when he tried to use them.
Without his newfound powers, Thane was quickly dominated by Thanos, and was thrown into the God Quarry itself, where he is destined to suffer until he is able to escape, if he even can at all.
Powers & Abilities
Thane's left hand has the ability to instantly change the very economics of existence as described by Ebony Maw. He lacks control of his power, thus everyone within a certain radius of him is killed.
Thane's right hand projects an amber construct which traps everyone within a certain radius of him and leaves them in a state of "living death."
Black Vortex Empowerment:
As a result of the cosmic power of the corrupting Black Vortex, Thane's cosmic potential was unleashed, vastly improving on all of his previous abilities and bestowing additional ones. He has used his cosmically enhanced power to encase the entirety of Spartax in his amber construct.
He lost this power at a unknown date.
Phoenix Force Empowerment:
As a Phoenix Host, Thane was capable of emitting blasts of energy so powerful that they could destroy a planet easily, and wipe out a squad of battleships. His stats were increased massively, to the point that he could brawl with a Thanos in his prime without being badly hurt in the process.
However, Thane lacked the psionic powers that a Phoenix Host usually has, which may be due to not being originally a telepath himself.
He was given a containment suit by Ebony Maw, which alters his powers so they can only be utilized through direct contact.
Unless he has the containment suit by Ebony Maw on, his powers are unstable, which unfortunately results in people getting hurt or killed.
As part of the Special Ops assignment, Infinity (13), a character by the name (Modern) Thane teams up with your agent for a Mini-Boss battle in Mission 3 - The Search for Thane.
"The hunt is on for the mysterious Thane. Whoever he is, Thanos wants him... which means we have to do everything in our power to keep Thane out of his hands." - Avengers Alliance