"No More Mutants" -Wanda Maximoff aka the Scarlet Witch
Spinning off from Avengers Disassembled, all of the A-listers of the Marvel superhero community gather to Genosha to decided on Wanda Maximoff's fate after what she did in Avengers Disassembled. Obviously, some heroes want to end her life since she is a high-level risk and had already killed some members of the Avengers while others decide that they shouldn't even consider the idea.
As the heroes are bickering, Pietro "Asswipe" Maximoff aka Quicksilver decides to save the day by convincing her sister to create a parallel universe where mutants rule the world with Magneto and his family as it's leader. Every hero within the meeting eventually gain their perfect life. Scott Summers and Emma Frost are married, Peter Parker is a big-time celebrity married to Gwen Stacy and has a son, Kitty Pride is a content schoolteacher, but some got the short end of the stick like Luke Cage who is a leader of the human resistance and Steve Rogers who was not encased in ice and is now an old veteran. There were only two people who were not affected by Wanda's spell: Wolverine and Layla Miller. Wolverine's broken memories eventually worked to his advantage as he is the only one that can remember what happen while Layla Miller is a mutant girl that could help other people see through the illusions. Wolverine and Layla Miller slowly build a force that would resist the House of Magnus and in their final controntation, Wanda Maximoff spoke three words that would have huge ramifications in the Marvel Universe:
"No More Mutants"
Through the three words that Wanda spoke, about 90% of the Marvel Universe's mutant community had lost their powers which pushes Scott Summers to lead the remaining mutants into a new direction. The conclusion of the House of M also shows the ressurected Clint Barton, who is seen within the ruins of the Avengers Mansion and clueless as to how or why he is still in the Marvel Universe.
The House of M spawned two storylines: Decimation is an X-centric book that covers the remaining powered mutants strivng for survival and the famous Civil War where the Superhuman Registration Act goes into play and divides the heroes into conflicting parties.