Jolly Green Sammy's Freakish Cro-Magnon Skull, Emporium Division, Kitchen Subdivision, and finally -- finally -- I get to cut to the chase: Long story short, because There Can Be Only One, Partially Reconstituted Sam guts his Lucifer's Cage doppelganger like a fish. "VIOLENCE! WANTON ACTS OF UNREPENTANT SAM-ON-SAM VIOLENCE AND GOOOOOOOOOOOOORE!" Lucifer's Cage Sam immediately drops to the faded linoleum, dead, because everyone knows knife wounds to the abdomen are instantly fatal, and his eye-searingly white essence, or whatever, spurts upwards from his rapidly cooling corpse to slam into Partially Reconstituted Sam, who shudders and jerks just as...
...Jolly Green Sammy does the same in the panic room. This time around, the epileptic spasms seem like they're never going to end. And they're really, really funny. "Higher! Faster! Higher! FASTER! Wheeeeee! [Slurp!]"
Castle Crowley. In the establishing shot of the Castle façade, we can see that Castiel's already placed several of his fellows around the grounds to guard against demonic incursion. Just so you know. Meanwhile, down in Crowley's baroque dungeon, My Contemplative Baboo sits by himself, intently eyeing his Mason Jar O' Blood. Presently, Belthazor flutters in, and unfortunately for everyone's favorite Eurotrash angel, Castiel knows all about the assistance he's been providing Bobby and the boys over the last couple of episodes. Belthazor attempts to talk his way out of it, but it's too late, and Castiel spears him with an Angel-Smiting Scimitar. "GOOOOOOOOOOOOORE!" Belthazor drops to the floor, and the camera leaps outside to take in the Castle façade as the searing white light heralding his death bursts upwards from the dungeon to pour through every window until a shockwave shudders out towards the screen, and in an amusing little touch, a haze of rent Belthazor feathers flutter through the air as the angel's death light gradually fades away. Heh.
And once the pyrotechnics have passed, the camera pulls a slow pan away from the Castle façade to greet the Impala as it grumbles down a nearby side street. Dean kills the engine and the headlights long before the Castle comes into his view and, after the Impala's glided to a stop, Bobby and Dean disembark to peer through their binoculars at Castiel's compatriots, of whom there are at least a dozen. Just then, a low rumbling noise hits their ears, and when they turn to scan the night for a possible source, a roiling cloud of bitterly black demonic foulness races across the full moon now hanging low against the horizon. "Holy mother of God," Bobby breathes as hundreds of tendrilly demonic swirls erupt from the main bulk of the thing to streak across the sky, each and every one of them headed straight in their direction. "Get in the car!" Dean blurts, as an expression of abject terror washes across his face. "Get in the car!" he frantically repeats, shoving Bobby towards the Impala. The two manage to fling themselves across the seats just as the front line hurls itself at them, and the Impala gets flipped over and thrown to the other side of the road before the mass hurtles onwards to attack the Castle.