Latest manga from the creators of Eureka Seven tells the story of Ganta Igarashi, a boy who is wrongly accused of the murder of his fellow classmates and is sentenced to death. So he's shipped to Deadman Wonderland, a prison that doubles as a theme park (yes it even gets visitors to a place where murderous convicts are held). Soon as he arrives, he learns that he can manipulate blood as a weapon called a Branch of Sin. Those with these kinds of powers are known as Deadmen. Soon to find out that the prison's warden has other plans for him and has him and other fellow Deadmen compete in games of death and various other death matches for the sake of entertainment.
As it is, this manga is definitely not sugar and rainbows.
Power of the Verse
In terms of power, the majority of the cast is pretty weak. Ranging from at least wall level+ power to devastating entire rooms. Some characters barely above sound speed. The only exception being the Wretched Egg who can create class 11.4 earthquakes which can devastate all of Tokyo. Although there's a modern military (more like the near future but close to our weapons).
Other than that, there's some level of hax such as being able to combust blood into flames, using blood as a bomb, various poisons that can cause hallucinations to those that can blow up the body and one that can replicate physical damage like being hit by a truck or being trapped in an iron maiden while showing physical damage and one guy whose broken enough to copy such blood based abilities.