After the stop at Intersection IV, they're back in Winter's End, and the counter reads Scoti 72, Basket 71. Two skeletons are shooting at them before the intro is even over. They clear spiders and creepers on the way down, with water pushing the spiders back, and drop "down below where we were before, the little jumpy island." At the bottom is the room they've been collecting scrolls for.
Getting ready
There's a Potion of Saturation and a book of hints. "If you are having trouble finding all five Summoning Scrolls, flip to the next page." A quick count turns into a scare about only having four, until it gets sorted out. "Basket was right."
The saturation lasts five minutes, so nobody drinks it until "a dude's like, I'm here to kill you." Ender pearls get handed over, four of them, as a way to get back to safety. A sign in the middle spells out the rule: "Hint! Yaaros can only be hurt in melee combat!" "I kind of figured that was gonna be the case." There's also gunpowder lying all over the floor, and nobody can explain it.
The scrolls go in. "One, two, three, four." One of them asks the other to watch what text shows up during the fight, "because it's one thing we got screwed with before." On Basket's screen the potion goes down. "Bottoms up."
Back to the ground
The whole back of the room opens up. Charged creepers drop from the ceiling, some of them don't move, and some of them fly. "Oh, those creepers, when they blow up, they blow up a lot." One of them thinks a ghast is floating around in there. With jump boost from the area, the plan is to keep jumping and hit things on the way past.
Then the chat: "[Yaaros] Back to the ground, puny human!" The jump boost goes away, then comes back. Blazes show up, and Yaaros teleports around the room, blowing up the ground along the edges. There's lava in one corner.
Darkness
"[Yaaros] Darkness!" "I can't tell what's going on." One of them drops to half a heart and runs for the alcove at the start to heal. One of them is out of health potions, and then the saturation runs out. "He's right next to me." "I'm not healed up yet." The other one shoots creepers and keeps jumping so nothing can get close.
Then: "No, you did it!" "We're awesome." "I got him."
Winter's End is ended
"[Yaaros] I ... will ... return!" The armor took a beating, and one of them has lost a good diamond helmet. The crystal goes in a chest so the other one can grab it. They check the back of the room for anything hidden, since "in the last boss one" there turned out to be more level, but there's nothing here.
"And we didn't die." "I like not dying." Back at the monument, the chat says "Congratulations! You have defeated: WINTER'S END." "It's time to put another crystal on the shelf." "Four crystals left, man."
The counter still reads 72 and 71, and the emerald blocks stay at 8 of 12. The crystal going on the monument isn't shown on camera before the episode ends.