Episode 99 picks up on the stretch of Basket Castle wall where the cobblestone battlements went in last time. "We worked on that. It looks awesome." There's one more idea to try before the design spreads to the rest of the walls: a support pillar running down the wall under every second or third merlon. Basket is the only player in the game; the in-game chat shows only Basket's own lines and the server's save messages.
A wider template
The pillar doesn't fit at first. There's an even number of sections, so there's no middle to put it in. Basket widens the repeating template to four blocks, takes a screenshot "in case I screwed up and I want to go back," and shifts the stairs, slabs and torches over one at a time. The first pillar is cobblestone. From the ground it "didn't quite do what I wanted," so Basket digs it out and builds it back up as fences. "I think that's gonna be better."
Symmetry and a second pillar
Next Basket shifts the whole pattern over one block so the pillar lines up with the open spot where a defender would stand, then copies it to the next section. A viewer thinks the lack of symmetry is too much. Basket isn't sure ("I feel like it's pretty symmetrical"), but tries a second pillar anyway, and likes that too. Now some of the small windows sit right behind a pillar. "That's no good." Basket moves them so they're centered on the wall between the pillars.
A new kind of window
With the windows moved, the wall looks plainer than before, so Basket redesigns them. The old ones are two stairs with a small gap. The new one is wider: stairs facing each other with a slab at the bottom like a sill, and a chiseled block on top. Basket tries cobblestone stairs around it, and then a plain stone slab a viewer suggests, but "the color's wrong." There are no matching stairs to frame it with yet. "When 1.13 comes out, we can redo all the windows again." Two of the windows stacked on top of each other turn out not to be too close.
The other wall
There's still time, so the design goes onto the next wall. Basket lines up the pillars with three sections between them, marks the water spot, and runs low on cobblestone partway through. The piece by the corner will have to be a little bulkier as it turns. The pillars stop where they are for now rather than running all the way to the ground. Back at a crafting table, Basket makes more chiseled blocks and puts two of the new windows into this wall as well, even though they're "probably too close together."
Windows over arrow slits
From the ground, a viewer likes the new windows but not the old arrow slits beside them. Basket agrees the windows can still be used to shoot from: "you're just a little archer person, so who cares." The plan for next time is more of these windows in place of many of the arrow slits, the battlements with their support pillars along the rest of the walls, and maybe a diagonal version of the window. The credits run to the end with no gameplay after them.