It's a tough call, but some might say Doctor Manhattan from the Watchmen universe within the DC Comics framework is incredibly powerful. His manipulation of matter and perception of time gives him a significant edge.
The title of the most powerful in DC Comics can be debated. Characters like The Flash with his speed force or Wonder Woman with her divine abilities could also be in the running. It really depends on the context and the specific storyline.
One of the best is 'Final Crisis'. It involves a multiverse - wide battle against Darkseid. The story has complex plotlines and shows heroes from different corners of the DC universe coming together. Another great one is 'The Sinestro Corps War'. It explores the conflict between the Green Lantern Corps and the Sinestro Corps, with amazing space battles and character development. And 'Blackest Night' is also a top pick. It features the return of dead characters as Black Lanterns, leading to intense battles and emotional moments for the heroes.
Some of the most powerful DC Comics supervillains include Darkseid, Lex Luthor, and Doomsday. They have immense powers and often pose significant threats to the heroes.
The Enfield Poltergeist case is quite famous. In London, a family's house was plagued by poltergeist activity. Furniture moved on its own, objects were thrown around, and voices were heard. It attracted a lot of attention, including that of paranormal investigators.
It's hard to say for sure, but many would argue that it could be Superman. His powers are almost limitless - super strength, flight, heat vision, etc. In a crossover, he would be a force to be reckoned with against most Marvel characters. However, characters like Thor with his godly powers and the ability to control lightning could also give Superman a run for his money.
It's hard to say for sure, but many would argue that it could be Superman. His super strength, speed, flight, and heat vision are incredibly powerful. He has been shown to be able to move planets in the DC universe. In a crossover, he could be a dominant force, but he also has weaknesses like kryptonite that could be exploited.
For beginners, 'Green Lantern: Secret Origin' is a great start. It gives a good introduction to the Green Lantern concept and character. Another one is 'Superman: Red Son'. Although it's mainly about Superman, it has a unique take on the character in a different kind of universe which has some cosmic elements. And 'Flashpoint' is also recommended. It's a story that changes the DC universe in a big way and is easy to follow while still having a lot of interesting cosmic - related ideas.