Joss Whedon, the mastermind behind cult hits like “Buffy the Vampire Slayer” and “Firefly,” kick-starts post-Oscar blockbuster season this weekend with the long-awaited Marvel spectacle “The Avengers.” He recently spoke to us on the phone about what it was like to assemble a dream team of superheroes and movie stars and why his movie should be your top summer movie priority.

Although he is best known for his original works, Whedon was no stranger to dealing with established universes thanks to his work as a script doctor on other franchises, including the original “X-Men” adaptation.

“I think Marvel has a great nose for a director who has a passionate vision,” says Whedon, “who’s not famous for churning out big budget hits but will bring something a little bit fresh to the concept of the superhero movie.”

Indeed, over the past several years the studio has attracted such a broad range of directors for their individual superhero films that determining where “The Avengers” would fit was one of Whedon’s greatest challenges.

“There’s no way you could make a movie that would look like a Jon Favreau-Kenneth Brannagh-Joe Johnston movie,” admits Whedon, citing his directorial predecessors.

“I tend to be a tiny bit florid with my camera work and my dialogue, but hopefully, in a way, that feels [realistic]. The way that I can reconcile the difference in styles is that my own style is actually kind of smack-dab in the middle of what all those guys do.”

While the complexity of the “The Avengers,” arguably the first interlocking-universe picture of its kind, meant dealing with a slew of practical and creative challenges, the pay-off was being able to work with such star-studded cast.

“I felt very much like Nick Fury,” Whedon jokes. “He is [the] director of S.H.I.E.L.D. And that puts him kind of removed from everybody, even if he likes them.”

But at the same time, having so many characters to work with required a careful budgeting of screen time.

“Everybody is so interesting up against each other,” he says. But if he had to choose, “I would say I love the Bruce Banner-Tony Stark relationship.”

“Bruce Banner is the first guy Tony Stark has come across, really, who operates on his level intellectually who isn’t a villain. And the way Tony nudges him is endearing and cool.”

And although he worked with some of Hollywood’s hottest stars, Whedon insists that none of the on-screen rivalries carried over once the cameras stopped rolling. Instead, with the candid enthusiasm of a fanboy, the director gushed about how the experience was like a dream come true.

“The Avengers” is the kind of movie that I grew up wanting to make and thought they had stopped making,” says Whedon, insisting that despite all the CGI and special effects, his film is really just “an old-fashioned movie.”

“When I grew up, the summer movie was literally created as a concept. And all my life, I wanted to do something like the first Indiana Jones—something that was steeped in character, in love with the genre that it was portraying, had intelligence, had real acting, had a story that unfolded and wasn’t just a big premise that you already knew going in.”

If anyone could pull off a big-budget studio picture while maintaining creative integrity, it’s Whedon, whose passion and enthusiasm for the source material is nothing short of infectious. But even so, that’s not to say that “The Avengers” was all play and no work. When asked what his ideal superhero power would be, the director didn’t bat an eye.

“I would have the power of invisibility,” he says. “And then I wouldn’t have to show up for as many shooting days.”

“The Avengers” hits theatres May 4.