"Epic" may be the thinking family's best Saturday matinee of the summer. And the date movie of the season.

This grandly conceived, impressively mounted swashbuckler marshals characters coldblooded, heroic and lovably goofy, "Avatar"-worthy fantasy visuals, action and romance, to a stellar payoff.

Oscar-winning director Chris Wedge has great silly-cartoon credentials. He helmed the first "Ice Age" and still provides the screechy vocals for that ongoing series' skittish sabre-tooth squirrel, Scrat. Here he moves to a new level, raising the sometimes woefully tired genre along with him. "Epic" shows that it's possible to bring a fresh, ambitious approach to feature animation without disowning its traditional virtues and strengths. It's fun with a sense of grandeur.

Like many fables, "Epic" begins in the forest. Unseen by humans, nature is locked in a timeless struggle between the colorful powers of growth and the dark forces of decay. Not simply the flora and fauna: There are little warriors actually duking it out.

The Leafmen, samurai-like defenders of blossoming life, ride hummingbirds and serve warmhearted Queen Tara. Their adversaries, Mandrake and his army of Boggans, spread rot. The voice casting is apt. Beyoncé is the honey-voiced incarnation of Mother Nature. Her opposite number is played by diabolically delicious Christoph Waltz. The clever, energetic script gives the devil his due, noting that decomposition feeds the forest, but favors vibrant green over ash gray.

Prof. Bomba (Jason Sudeikis), an impractical dreamer-inventor, hasn't yet snapped a photo of the forest-dwellers, though his absent-minded quest has fouled up his relationship with his teen daughter M.K. (Amanda Seyfried). Shrunk down to grasshopper size through once-upon-a-time hocus-pocus, she joins the dashing Leafman Ronin (Colin Farrell) and his dreamboat protégé Nod (Josh Hutcherson). M.K. holds her own in the action scenes yet finds time for miniaturized flirting.

The setting is bizarre and the jokes often loopy, but everyone stays true to the reality of their roles, and the narrative is never sacrificed for a showstopping punch line. There's scrupulous attention to detail in the film's magic-realist look, which transforms sparrows' skulls into battle helmets and dandelions into Afro-haired plant people. The images have a hallucinatory tingle.

Initially the film feels calculated, as it seesaws between emotion-heavy girl scenes and breathtaking breakneck action for the boys. It wants to be warm and cool. But it finds its groove and rolls ahead with a jolly momentum, introducing new characters whenever a young viewer's concentration might drift.

As a snail and slug odd couple, affably spacey Chris O'Dowd and cocky Aziz Ansari have an amiable one-upping rapport. Steven Tyler, of all people, does an agreeable turn as a sage old caterpillar, and Bomba's excitable, goggle-eyed three-legged pug tumbles through any scene that needs a gag.

They're not vibrant, one-of-a-kind creations; there's not a Wall-E in sight. But as instantly digestible archetypes, they're amusing and primary-colors bright. Waltz is a big, hearty, malevolent caricature as the king of corrosion. Seyfried makes her Everygirl character fun and humorously fallible. Her vocal contortions are ticklishly funny when she runs afoul of a mouse and later zaps up a chain-lightning charge of static electricity. Grab your favorite child or grandparent or date and go live happily for 102 minutes ever after.