The episode opens at the gate to the Blackroot, with one of them running behind the others. "I'm the laggard." The party is johnfal_92 and Dash (dash10138), going by the nameplates. Scoti isn't on the server. The goal is up on a hill across the way, past a path and a bridge one of them found on the way to the Overgrown Cave.
A temple in the jungle
They go right at a fork and spot a structure through the trees. It's a temple, marked as a point of interest, and the name floating over the entrance reads Tlaxan Ziggurat. The first thing anyone notices is the spawners on either side of the stairs. Somebody wishes they had brought a combat bed. Nobody has enough string, and the one who does left it behind.
Spawners on every level
The ziggurat is stacked with them. Zombies on the ground floor, skeletons on the next level up, creepers you can hear before you see, and a blaze spawner inside. "There's a creeper behind you, Basket!" Zombies drop off the roof and knock one of them down, and the general verdict is "this is a bad entrance."
Inside, the staircase is partly blown up, with lava at the bottom. The server lag gets bad enough that one spawner can't be broken at first. The creeper spawners turn out to be under the stairs, one on each side. One of them leaves the creepers a path on purpose so they come one at a time. A bow takes care of the blaze, with a warning not to step in front of it.
Then the chests. One of them gets a new helmet, and there are apples. "Don't fall in the lava."
The dungeon lobby
Past what looks like a trap (it isn't), a sign says this is where players teleport when leaving the dungeon lobby. Below is a big sandstone hall with bookshelves and pillars, and a row of signs answering questions. "How do I unlock a wool dungeon?" "How do I bring a new player into an unlocked wool dungeon?" "Yay, we found it!"
They read the rules out loud. Once you have access you can come and go as often as you like. All dungeons and everyone's access reset periodically, and after a reset you buy access again. Beating the same dungeon more than once gives no extra skill points.
Paying for the key
The Gatekeeper sells a White Key for 20 concentrated XP. Put the key in the item frame, get at least three players on the pressure plates, and the dungeon unlocks. Here's the summary they settle on: "pay XP for a key, put the key in the item frame, have a group of three people, then you can unlock the dungeon."
There's also lobby quick travel, so next time they can teleport straight here. That costs three Imperial Coins, not XP. One of them is worried because some of their coins won't stack with the others, but it works: "You have enabled quick travel."
Do we go in?
The catch is the third player. Each unlock is one instance per player per reset, and you can't walk into someone else's. If Dash is their third, does that use up Dash's white wool for the week? Nobody is sure, so they leave it up to Dash. "No pressure, man." There's about 20 minutes left in the stream, and no telling if they'll get to play together again this week.
They decide to go look. Someone already has a White Key. The rest is a quick trip to the chests: a speed potion, some real armor, and a repair on the leather. "I guess I'm ready."