Some TMNT stuff was always meant for grownups.
The Decider had some psychic powers, including the ability to sense minds and to be able to control those who were weak-willed enough for him to do so. He used this power to manipulate voters into getting him into office, and once he noticed some "unique minds in unique bodies", he ordered them to commit crimes for him, such as rob banks. He also commands them to kill the Springfield police commissioner, who was one of the few he was unable to control, out of worry that the commissioner was close to uncovering his plot.
When Splinter and Casey Jones found out what had happened and why the Turtles were committing acts of evil, Splinter taught them a psychic defensive mind trick. It didn't work initially, and The Decider still had them prepped to kill the commissioner, but when they overhear the commissioner say the word "Case", Leonardo is reminded of Casey and snaps out of his mind-controlled state and gets the others to do so, as well.
The Turtles pretend to still be under his control and report back that the commissioner is dead. The Decider holds a press conference to announce the commissioner's murder, but the commissioner himself shows up and says that a tipster had informed police that the mayor had lost his mind and was planning to have him assassinated. The Decider runs back into City Hall and sees the Turtles, who he orders to protect him. The Turtles reveal he no longer controls them and intimidate him, smashing his chess board. The Decider continually repeats that he is The Decider, and warns of "giant turtles", which gets him carted off to a mental institution.
Powers and abilities
- Psychic powers: Through unknown means, The Decider developed psychic powers. He can "sense" other minds, and is able to take control of those of weaker wills telepathically.
- Chess set: The Decider owns a chess set, which also has custom Turtle pieces, that he uses when controlling his targets. It is unknown if this chess set is necessary for his powers to work, if it's just a conduit, or just a visual representation.
- The Decider is a rather cartoonish parody of former United States president George W. Bush. The Mirage Studios staff were rather vocal detractors of Bush's time in office, and even though this issue was published at the tail end of his presidency, this was their (specifically, Jake Black's) blatant way of lampooning him. The Decider's name comes from a press conference where Bush stated that he was "The Decider", and while that is an acceptable term, many found it was either archaic (preferring "decision-maker") or just saw it as an excuse to make fun of the president's turns-of-phrase.