Origin and Wildcats
Tao was created by scientists but no one ever knew why. He was left in a base with other things like him until Savant and Mr. Majestic came looking for people to replace the WildC.A.T.s when everyone thought they were dead. He manipulated a worker at the base to let him out so he could join the team. When he became a WildC.A.T. he started manipulating the other members into attacking enemy groups in a way that would eventually cause a Gang War. When his teammates found out what he had done they tried to kill him. To escape, he tricked a shape shifter named Mister White into pretending he was him. Tao had gotten three members of his team hospitalized and had blown up a nuke in Mr. Majestic's face in his escape, so when Mr. Majestic found Tao (the shape shifted Mister White) he didn't hesitate to kill him.
Tao was created by Alan Moore and Travis Charest. His first appearance was in WildC.A.T.s: Covert Action Teams #21.
With Tao presumed dead he was able to leave and start a new life. He started the criminal organization that the comic Sleeper is focused on. He recruited Miss Misery, Holden Carver and another super powered being to be his Prodigals, three bosses that controlled all the underlings and completed various tasks for him. With his organization, Tao was able to meet the group of people who controlled the world. He became one of them and started going to their meetings, using his powers to manipulate and maneuver them into doing what he wanted. Eventually deciding he didn't like what they were doing, he turned the group to his own ends, namely destruction and chaos whenever possible. Tao's organization was eventually undone by one of his own Prodigals. Holden Carver was a double agent placed in Tao's organization by John Lynch. Tao had of course figured it out and both he and Holden knew it, but Holden continued to work with him, his allegiance to IO and Lynch in question (even in his own mind). It took some time, but Holden's alignment was revealed in an event that resulted with Tao turned over to IO where he sat in a large glass tube with his tongue cut out.
After the events of Sleeper in which Tao was finally caught, there initially wasn't much known about what happened to him. It was assumed that he was still in IO custody, but it appears that was not the case. It turned out that he had escaped at some point, regenerated or regrew his tongue, came into possession of the restored Void, and was making rather elaborate plans to continue his work of destroying the world. Tao's first move was to use Void to send various heroes into the future to show them a world that had been destroyed. Heroes from several prominent groups in the Wildstorm Universe saw the future but for whatever reason the actions they took on their return to the present didn't have the results that Tao wanted (or change it like they wanted). That was until Nemesis. When she went into the future and came back she reacted in the way Tao wanted her to and in her efforts to stop the end of the world, actually started it. When last Tao was seen before World's End had begun he was already prepared. He had an army of SPBs in storage, he'd planned an uprising of another group of SPBs, he was still in possession of Void, and it appeared that he had set up a backup body with his personality in it in case anything should happen to him. After the end of the world Tao used Void to capture Providence, which gave him control of two reality warpers. At first he used them subtley, expanding his abilities so he could speak directly into the brains of heroes across the planet. After that he somehow began to take their powers into himself in preparation for his next target, the reality warper known as Max Faraday.
Tao's main power is his unbelievable intelligence. According to his files "Tao's grasp of tactical, strategic thinking has achieved a seemingly transcendent level which utterly surpasses normal human consciousness. Without any recognized psionic skill such as telepathy or telekinesis, Tao's mind has entered conceptual territory so far above our own that one might as well attempt explaining quantum physics to an ant." Tao's brilliance usually shows itself in his ability to quickly figure out just about anything, from how to operate complex machines, how systems (social or technological) work, what the perfect strategy for any given situation is, even down to personal secrets, flaws, traits and weaknesses of people he's only just met. These kinds of information are then used in the manipulation of individuals and whole cultures for his own ends.
How he uses his intelligence on others, to manipulate and control them, is something that seems to be hypnotic or psychic, but isn't. According to scientists and people that have looked into Tao's creation (people like John Lynch), everything Tao can do comes from his intelligence. He's just so smart that somehow talking to someone, even briefly, is enough for him to completely control their way of thinking. "He redefined genius, and listening to him talk was like playing Russian Roulette...with his words as the bullets" - John Lynch. With nothing other than words, Tao has been able to put a superhuman in a coma, implant false memories, remove real memories, control physical actions as well as the reality that his listener experiences. In most cases though he allows his listener to retain control of their thoughts (or at least believe they do) and manipulate them in more subtle ways. Tao isn't limited to verbal communication, as shown when he had his tongue removed. He is just as dangerous with gestures and facial expressions. Any form of communication is a weapon for Tao. In addition to this, Tao is a decently skilled martial artist and has a high tolerance for pain so he's not helpless in physical combat should that ever be a last resort.
Since Tao's ability works by controlling how someone thinks, it relies on at least some level of intelligence and as a result, it doesn't work on people who are incredibly stupid.
After capturing Void and Providence, Tao began slowly leeching off their powers so he could control reality directly instead of working through them. The first thing he mastered was the ability to use his normal powers without his target knowing. He no longer needed to speak directly to someone, he could manipulate them from a distance (like Majestic in Hawaii or Jackson King in space) without them even knowing. He's also demonstrated superhuman reflexes, telekinesis, teleportation, transmutation (turning bullets into butterflies and turning Maul into Jeremy Stone), superhuman strength, energy manipulation and even an amazing understanding and mastery of magic.