Basket opens in the enchanting room at the plateau base with a rundown of everything done since last time, then heads down to the zombie spawner under the base to turn it into a proper grinder.
Catching up
First stop is the chicken coop. The eggs from last episode "didn't really pan out," so Basket ended up luring chickens there and breeding them. Hoppers sit underneath to fill a chest, but "I think I positioned this hopper wrong." Out on the plateau, a dirt pillar now marks a hole Basket dug straight down to the spawner.
Then come a few clips. A new diamond pickaxe got Silk Touch on the enchanting table, so Basket kept it "for getting diamonds and stuff." A basic grinder at the spawner brought in experience, and the next enchant was a Fortune II pickaxe for the diamond ore Basket had been saving. "32, not bad." Those became diamond armor and a few more diamond pickaxes. More zombies paid for the boots. "Yay! Success!"
"And that catches us up to now." Basket is in a full set of diamond armor.
Just the one spawner
"If you're within a 16 block radius of the spawner, then they'll still spawn," so Basket clears out the stone around this one, hoping for a second spawner close enough for a double setup. "Looks like there's no other spawners around this area." The cleared room shows the range, and Basket lays out the plan: water washes the zombies into one channel, they swim up a tall column, then drop back down hard enough to be "down to one health."
The water elevator
The elevator goes in with glass in the middle, since signs can sit on glass and "it would look a lot cooler." Basket jumps in to show the ride: "So imagine you're a zombie." The first test zombie takes "a couple more hits," so Basket plans to raise the drop. A lower test changes that plan, because the zombies "seem to actually die right away on impact." Basket keeps it at what looks like "a 22 block fall."
Not every zombie cooperates. Some try to swim toward Basket instead, and some bump each other back down. Torches shut the spawner off while Basket works, and the zombies return the favor: "They're bringing my torches and stuff that I lost down there." The debug screen puts the entities in front of Basket at about 28. A future splash potion of healing could finish them all at once, and maybe "200 zombies to get from 0 all the way up to 30."
Back up top
At 30 levels another diamond pickaxe comes off the table with Efficiency IV. The Silk Touch pick goes in a chest: "I don't know what I'm saving it for." The egg chest is packed ("Wow. That's a lot of eggs"), though a few chickens have been bumped out of the pit. Basket stores some sugar cane, sleeps, and goes back down.
Signs on signs
The bottom needs a rework so zombies leave the spawner's range before lining up for the single path up. Basket hangs signs on other signs to hold the water in place, so breaking the first one drops them all. Then the water finds dead spots. "I really made this complicated."
After a few more rearrangements the flow pushes the zombies the right way, and the test works. "Okay so they are, at least that guy is. Okay so I guess that worked, good."
The episode ends with Basket alive at the grinder, checking the diamond chestplate and leggings. The plan is to let zombies build up and spend the levels on "those other two picks that I had and then maybe some of this armor."