For the first time since "Scream," the slasher genre shows signs of life (was that in poor taste?) in "Freddy vs. Jason," a franchise merger that pits hockey-masked psycho Jason Voorhees from the "Friday the 13th" movies against "A Nightmare on Elm Street's" dream-invading bimbo-killer Freddy Krueger and his knife-blade glove.

The scenes in which these two unstoppable supernatural slayers are literally at each other's throats prove to be everything fans of such movies could hope for as they hack, cut, beat, tear and toss each other around, first in Freddy's dream realm (where the burn-scarred nutcase has tapped into Jason's subconscious), and later on Jason's home turf at Camp Crystal Lake after Freddy has been drawn into the real world. Their super-violent showdowns are like John Woo fight scenes with all the elegance sucked out and replaced with brutal fury.

Unfortunately, the rest of the movie is largely the same tired old crap -- 25-year-old half-talents playing unconvincing high-schoolers stalked through the dark by one or the other of our killers. Any bouts of creativity in the script are almost immediately squelched by low standards of hack filmmaking, as evidenced by the boring expository prologue in which Krueger (Robert Englund) blabs on and on about his backstory, then explains the plot: He's awakened Jason (Ken Kirzinger) from the dead by invading his psyche (as a vision of his abusive mother), sending him to Elm Street to rekindle the fear Freddy needs to thrive in the dreams of his hometown teenagers and begin anew his own killing streak.

For the movie's first 30 minutes, all that's new are the actresses' almost ubiquitous breast implants as they go through the horror movie paces of having easy sex, taking showers, hearing scary noises, discovering their boyfriends' mutilated corpses, seeing Jason, running through the night in wet T-shirts, tripping on something so Jason can catch up, then getting gutted as Karo syrup and red dye No. 5 splatter across the screen. Even before the opening credits, the movie is knee-deep in clichés.

"Freddy vs. Jason" only begins to get interesting when the kids who survived Act One realize the town has participated in a huge cover-up of old Elm Street murders and fed its children dream-suppressant drugs to keep them from ever even knowing the name of Freddy Krueger. But with that cat out of the bag, there's no escape. As the cast gets tired running from Jason, they know Freddy's waiting for them in their sleep.

But even when handed this golden B-movie premise and several interesting twists (all the kids who knew about Freddy are locked up in an asylum where Jason pays a visit), director Ronnie Yu ("Bride of Chucky") stubbornly refuses to steer away from formula or patch up plot holes. The underlying and all too correct assumption that most slasher flick fans have low standards still runs rampant in Hollywood, and I guess the thinking goes, why waste originality on those who won't appreciate it?

So Yu cranks up the heavy metal soundtrack and his killers cut loose, as the inevitable virginal heroine (Monica Keena, "Dawson's Creek") and her dwindling number of friends seek a way to stop them -- often with unintentionally laugh-inducing lines of dialogue like, "Wait! Freddy died by fire, Jason by water! How can we use that?"

The two franchise anti-heroes are finally pitted against each other when Jason gets off his leash and starts killing too many victims before Freddy has a chance to slay them in their slumber. How Jason winds up in Freddy's dream domain is a surprise I won't reveal, and how Freddy is pulled into the real world at the summer camp where Jason's bloodlust was born is even better. Despite being encumbered by a whole lot of ridiculously convenient contrivance (What luck! A huge, brand new, fully-charged propane tank at a camp abandoned 50 years ago!), the picture's finale is a hum-dinger.

Now, why couldn't the rest of "Freddy vs. Jason" be so entertaining?