Like its horde of monster villains that only awaken to attack China every 60 years, Zhang Yimou’s The Great Wall is slow to come to life. The opening scenes, in which a band of pan-European mercenaries led by Irishman William (Matt Damon) and Spaniard Tovar (Pedro Pascal) ride through the Northern Chinese countryside, evading capture and seeking to steal the secret of gunpowder in order to sell it back home, are plodding and hokey, with dialogue marked by exchanges that were clearly reverse engineered from the quips (“I’ve been left for dead twice. It was bad luck.” “For who?” “The people who left me.”) Once William and Tovar arrive at the Wall itself, though, some color and life begin to flow into the movie. This trend will continue; any scene that features no Chinese characters (Willem Dafoe also appears) is comparatively dull and drab. Perhap Zhang is tugging back at the problematic “white savior” conventions of the screenplay by reminding us that the only reason the Europeans (or the audience) are present is because of the Chinese setting and characters. Still, the first major battle sequence is the movie’s least thrilling, consisting largely of noisy effects shots alternating with shots of people reacting to them, like a chintzy episode of Charmed. But it’s in these same scenes that we are introduced to the “Nameless Order,” The Great Wall’s fictitious military legion tasked with repelling the army of beasts. The more time we get to spend with them, their innovative battle tactics and their byzantine hierarchy, the more the movie starts to have fun, kicking off a snowball effect in which each set-piece outdoes the last, building to an implausibly rollicking finale.