Iron Man actor Robert Downey Jr yesterday brought cheer to 37 children, leading them in a pledge that turned them into "little superheroes". The 37 children, all battling critical illnesses, are beneficiaries of Make-A-Wish Foundation. They were playing games related to the Avengers superheroes movie franchise in the expo hall at Marina Bay Sands organised by the charity when the actor made a surprise visit. Downey, who is here to promote the new movie Avengers: Infinity War, handed out goodie bags to the children and spent about 30 minutes with them. Muhamad Azri Firdaus, 11, who was diagnosed with Fallot's tetrology, a congenital heart defect, said: "I can't believe I just met the real Iron Man in person. I love super heroes and Iron Man is my favourite. I even have an Iron Man costume."