Boom. "Blackwater," the long-awaited, penultimate episode of "Game of Thrones" second season, explosively made good on the promise of HBO's epic fantasy series. Despite funding "Game of Thrones," HBO apparently isn't as rich as a Lannister, so even though the show primarily depicts a sprawling medieval-style war, budgetary reasons keep the clashing armies off-stage. It's like "Game of Thrones" April 2011 debut lit a fuse that, after 18 episodes and more than a year, finally ignited the bomb. Or, more appropriately, the napalm dragonfire. Directed by Centurion's Neil Marshall and scripted by George R.R. Martin himself, "Blackwater" not only delivered the spectacle, it retained the emotional weight that gives the show such an impact. It also harks back to the era of sprawling TV miniseries like "Shogun" and "The Winds of War," when the big three networks ruled the broadcast kingdom.

"Blackwater" takes place over the course of a single night in King's Landing and the surrounding bay, surrounding the troops of both sides with a literal fog of war. An early scene on Davos' invading ship sets the tone of pre-battle terror as a soldier vomits in the hold, presumably due to nerves and not sea-sickness. Davos has a nice scene with his religious son, who says he has "faith in the Lord of Light, faint my the men and faith in my Captain," the latter part affectionately referring to his Dad. Davos' son isn't just a religious zealot.

On the eve of battle, Tyrion spends a night with Shae. Maester Pycelle, whom we see for first time since Tyrion sent him to dungeon, gives Cersei a small vial of poison. Bronn and his men visit a brothel and encounter Sandor Clegane, who nearly has it out with Bronn, but they have a drink instead. Reliably dickish, Joffrey demands that Sansa ceremoniously kiss his new sword, "Heart-Eater." Sansa has learned how to push his buttons, however. When he calls her stupid for asking where he'll be in the battle, she replies that of course he'll be fighting in the vanguard - passively goading Joffrey into getting himself killed.

Tyrion bids Bronn good luck and insists that they're actual friends. On the torch-lit battlements, panicky Joffrey provides an amusing foil to determined Tyrion, with Lancel and Sandor as supporting players. Cersei, Sansa, Shae and the rest of women of the court gather in a fortified room in the Red Keep. Ilyn Payne supposedly remains there to protect them, but seems more likely to execute the ladies lest a victorious Stannis take them hostage.

From the wall, they look out at the bay. Joffrey wonders what happened to the royal fleet. A single ship floats out towards Stannis' armada as it emerges from the mist. Tyrion calls, "Archers to your marks!" Davos does likewise but restrains them, upon realizing that the ship is empty. Davos then notices that the ship is leading a trail of green dragonfire. At Tyrion's Bronn looses an arrow, which ignites the flammable fluid. Davos shouts for his son to get down as a massive green inferno erupts in the bay, consuming dozens of Stannis' ships.

Stannis orders the ground assault, and when one of his officers protests "Hundreds will die," the would-be king makes a little face of bemused annoyance and says "Thousands." Sandor Cleghane leads the King's troops, and during the battle literally cuts a couple of guys in half (one horizontal, one on diagonal). He starts to freak out with all the fire around, however, and though Bronn saves him from an attacker engulfed in flames, Sandor's nerve breaks. (The show doesn't need to remind us that Sandor was horribly burned by his brother - it's literally written all over his face.) Despite being the toughest SOB in Westeros, Sandors returns inside the wall and declares, "Fuck the Kingsguard. Fuck the city. Fuck the king," looking right at Joffrey.

In chambers, Cersei guzzles wine and demands that Sansa join her. Sansa really gets under Cersei's skin, perhaps because she reminds the queen of her own unwelcome arranged marriage when Cersei was a girl: "I was sold like a horse to be ridden whenever he liked." She makes sneering remarks about Sansa's first period and her group prayer, but Cersei ultimately gives into despair, while Sansa's higher spirits see the young woman through. Cersei also suspects that Shae isn't who she claims to be.

Stannis orders his men to put up the ladders - because you can't have a proper siege scene without ladders, after all - and kicks Lannister ass on a seemingly remote part of the wall. His soldiers find shelter against arrows and falling rocks by marching under an upside-down longboat - that old trick - and have at the mudgate with a battering ram. (They're symbolically doing to the city what the Lannisters fear they'll do to the city's women.) Joffrey retreats from the wall at Mommy's orders. Who'll lead the counterattack? In the absence of takers, Tyrion steps up. At first the dispirited troops ignore him, but Tyrion gives a great pep-talk, urging the men to defend the city not out of love of duty or the kingdom, but to protect their families and themselves. He winds up with wonderfully macho line, "There are brave men knocking on our door. Let's go kill them!" It's Tyrion Lannister's finest hour, full of wit, courage and his philosophy of self-interest.

Fearing that the wall could fall, Shae sends Sansa to hide in her quarters, suggesting that Stannis could protect her, but the Lannisters surely will not. But someone's in the room with Sansa - is it a cowering Joffrey? No, a shaken Sandor Clegane, who's stopped by en route to desertion. He says he's going to flee North and offers to bring Sansa to Winterfell. (Do it, Sansa! Do it!) Sansa elects to stay, and Sandor gives a great speech that culminates with "The world is built by killers, so you'd better get used to looking at them."

Tyrion leads troops from secret passage and literally cuts off one guy at the knee before they ambush the troops with the battering ram. Tyrion's team wins! "Half-man! Half-man!" But what's that sound? A horde of Stannis' guys are heading their way! Tyrion says "Fuck. Me." In the melee one of the Kingsguard turns on Tyrion, slashing him across the face. Podrick the page saves Tyrion. Cersei, seated on the Iron Throne with her youngest son, tells a story about a lioness, her cub and their enemies in the animal kingdom - honestly, so much else was going on I had trouble keeping the thread. But she's clearly about to poison them both rather than fall into Stannis' hands.

Back at the mudgate Tyrion collapses but the cavalry arrives, including a knight on a white horse? Who the heck? Why, it's Ser Loras, finally getting revenge in the name of his late boyfriend Renly. And Tywin's there too, with his troops. Cersei drops the poison! A furious Stannis is forced to retreat! The bad guy loses! The other bad guys win!

Notes
I don't think "Blackwater" spelled this out, but the royal fleet clearly picked up reinforcements in Tywin's troops and the forces loyal to Loras and the Tyrell family.

A trivial detail: the sick soldier at the beginning puked in a container brimming with liquid. Since no one complains that he spewed in their water supply, I wonder if it's just a big barrel of barf.

I liked how Varys feigned ignorance of Podrick's name was suiting up, and then Tyrion feigned ignorance of Shae's name shortly thereafter, to conceal their relationship to the court.

Varys: "I'm not entirely sure what you're saying." Tyrion: "I'm entirely sure you're entirely sure what I'm saying."

Bronn's tavern/brothel has a tree in the middle of it - I wondered if that has a connection to the Godswood, that big tree where they pray in Winterfell. Prayer provides a running motif throughout the episode.

If memory serves me right, in the books they made a point of observing that the dragonfire burned more powerfully than they expected, a possible repercussion of the hatching of Dany's dragons.

A few nitpicks about the siege scene. Scale-wise, it seems more like a skirmish than a battle royale, with the bank particularly underpopulated when Tyrion's troops fought the forces at the gate. Plus, in some of those grisly money shots, the blades seemed to slice through bone with no resistance, but I'm not really complaining.

Without spoiling specifics for people who might want to read A Clash of Kings, I'll say that in the book, Tyrion devised a more complex and spectacular tactic for devastating Stannis' fleet. Not surprisingly, it was clearly beyond the means of the HBO show to dramatize, but the substitute effect proved quite satisfying.

Here's the clip for next week's season finale: