X-Men 3 The Last Stand

For the first time, mutants have a choice: to preserve their uniqueness, even though it isolates and alienates them from humans, or to give up their powers and become human. The differing views of the two mutant leaders, Charles Xavier, who believes in coexistence, and Magneto, who preaches the right of the strongest, are put to the ultimate test and ignite a war that could end all wars.

Genetic researcher Dr. Kavita Rao invents a serum called "Hope" that fights and can even cure mutations. This controversial substance is now circulating among the X-Men, particularly with Hank McCoy / Beast, who wants to combat his difference with it. However, not everyone is convinced of the serum's effects, and it quickly evolves into a deadly weapon that the X-Men must unite to fight against.