This is the first video of the Redstone Gift Basket, "my new series where I'm going to explain redstone things." It opens on the finished farm in Basket's survival world: spiders gather, a button sends them up, lava burns them, water puts them out, and one hit kills them all for the XP. Then a creative world takes the machine apart piece by piece, and the video ends on digging out a spawner room.
Lava/Water Bucket Dispenser
The first piece places lava for a moment and picks it back up. A piston sits under a block, with redstone dust or a repeater running off it. The incoming signal becomes a one-tick pulse that fires the dispenser holding the lava bucket. A second line on a short delay ("I believe it's two delay") powers the block beside the dispenser so it takes the lava back. The farm has one for lava and one for water, and any signal, "no matter the length or the strength of it," fires each once.
Hopper Timer
Two hoppers point into each other. A comparator runs off either side into a block topped with a redstone torch or dust, and above that two sticky pistons face in with one redstone block between them. Items pass back and forth, and the item count sets the delay. When one hopper runs empty, a torch gives a brief signal to send on.
XP Redstone Demonstration
Pink blocks mark the lava mechanism on one side and the water on the other, and the spiders collect under purple blocks in the middle. The button pulls the purple blocks back so the spiders come up, fires the lava, and lets the hopper timer run. When it empties, the water comes on. The spiders are "down to one heart," and a sword finishes them from behind a half slab.
Twenty items was right on Basket's server; if the spiders die early or survive the hit, change the count. An orange section came later, because "I wanted to collect a bunch of string." Its lever puts the timer in charge of the button and breaks the water line, so the spiders burn up and their drops fall to a hopper.
The Spawner Rooms
In spectator mode, Basket tours one of the three spawners. Spiders drop about ten blocks, out of the spawner's range, into water streams split by signs, with few walls to climb. They bunch up in a narrow channel, and a climber leads the clump up under the purple blocks. One button press and one sword swing later, the XP is in. The drops ride a dropper tower, which the commentary calls "sort of laggy" and would swap for a glass item elevator.
Clearing a Spawner Room
On a fresh creative copy, clear four blocks out on every side of the spawner; a ring of torches stops spawns while you dig. The floor sits ten blocks down. Dig a trench down the middle, set the water source one block back, run it six blocks and let it drop. Signs go down the center with water on both sides, and a bottom stream pushes the spiders into a one-high hole toward the collection shaft. Redstone lamps go in the ceiling last, and the torches come out.
The video closes on Basket's character back in the fort, collecting XP.