Prepare to be amazed.

It’s all been building to this.

By “it,” we mean a decade of Marvel Cinematic Universe adventures that made superhero films the coin of Hollywood’s realm.

“This” means “Avengers: Infinity War.” And while “War” is just the first of a two-part adventure, it’s a spectacular achievement in its own right.

In short, Marvel has done it again. Lather, rinse, generate (well earned) millions. They make it look easy, don’t they?

The action begins instantly, as the villainous Thanos threatens some of Earth’s mightiest heroes. No spoilers here, of course.

Just get ready to flinch.

We’ve seen Thanos before, even those who have never cracked a comic book. Previous MCU films teased the legendary foe, but nothing prepared us for this. Josh Brolin supplies both Thanos’ voice and mannerisms, goosed by glorious CGI effects. If you thought Killmonger was a colossal leap forward in Marvel villains, just wait.

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With Thanos front and center, “Infinity War” immediately raises the stakes. That’s often a problem for a genre where figures shrug off countless blows before saving the day.

Not here. There will be pain. Blood. Loss. And jokes. Lots of jokes.

And, as we’ve been teased for months, more heroes than you’ve ever seen on one screen before. Yes, Spider-Man (Tom Holland) returns, slightly wiser but still unsure of this whole superhero business. The Guardians of the Galaxy join the fray, too, their sophomoric wisecracks intact.

Doctor Strange (Benedict Cumberbatch) plays a critical role in the fight to smite Thanos. His nutty mysticism is a welcome refrain from the punch, and then punch HARDER, school of super action.

FAST FACT: The very first Avengers lineup circa 1963 featured Thor, Iron Man, Ant Man, the Wasp and the Hulk squaring off against Loki.

Directors Anthony and Joe Russo (“Captain America: Civil War”) bring out the very best in the MCU formula … again. They set our heroes loose in a number of connected tasks, all to stop Thanos from acquiring the remaining Infinity Stones.

What’s that? You’ve got some catching up to do.

Those who are all caught up may feel downright giddy. The action is immense, towering over previous efforts with their sense of danger. It’s like the minds behind “The Walking Dead” whispered in MCU overlord Kevin Feige’s ear that not every hero needs to live to the final reel.

The stars still have time to bicker and throw comic haymakers between the fisticuffs. Once again, nearly every joke lands, even when delivered between earth-shattering jolts. It doesn’t make sense on paper, but the Russos are so firmly in control of the tone and story the comic relief is never compromised.

Remarkable.

So what’s wrong with “Infinity War?” You won’t see much character progression amidst the rubble. Thanos’ mission statement, to extinguish half of all living things, is both startling and simplistic. And not every beloved character gets the screen time he/she deserves.

How could they?

The film still allows Thanos a flicker of humanity. For all his brawn, he’s a conflicted monster giving his full attention to his inner turmoil. His connection to Gamora (Zoe Saldana) is particularly strong.

To put it less delicately, you’ll actually care about the moments between heart-stopping action.

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Just as effective? The underlying humanity that keeps bubbling to the surface. Call it a throwback to “Star Trek II: The Wrath of Khan.” How much is a single life worth if it saves hundreds? What about millions?

You’ll be asked that question over and again. So will our heroes.

“Avengers: Infinity War” isn’t an exercise in nurturing characters or intimate plotting. It’s not meant to set up another series of tales or sell us on a particular new hero. This is war, superhero style. It’s hard to think of a more stunning declaration than this virtuoso performance by the Russos and Team MCU.

HiT or Miss: There’s no way “Avengers: Infinity War” could live up to the hype, right? Oh, yes it could.