This stream of Quern picks up where Episode 18 stopped, at the spoked wheel on the cave wall. The wheel gets solved early, but solving it only turns it upside down, and a second pattern is needed. Finding that pattern takes most of the hour, and it turns up on a banner seen from the lighthouse. The video ends with a battery that cannot leave its pedestal without shutting the room, and a plan involving a bucket.
Counting tally marks
"We just found this area here." The cave has a wheel with eight spokes that push in, and a chart on the wall drawn with the same rings and spokes, each segment holding a group of tally marks. Some segments are colored in. The plan is to push the spokes in number order, skipping the ones that are not colored.
A quick trip to another building settles how the marks count: "a horizontal bar is 1, 2, 3, 4, and then a vertical bar is five." Back at the wheel, the commentary counts up to fifteen and pushes each spoke in turn. "There we go!" The wheel turns around so its arrow points down. Through the bars of a gate beside it is a small room with a pedestal: "Oh, our precious, precious battery."
Upside down
The gate stays shut. The chart has a 1 in its corner, and the commentary suspects a second diagram exists somewhere. First, though, comes the idea that the same chart works with the wheel flipped. Two long attempts follow, counting each segment "which is here, which is actually here," with notes on paper. Neither opens the gate. "Either I don't understand what I'm doing, which is probably the case, or there's another one of these somewhere in the map."
The banner from the lighthouse
The search covers the cliff, the potion room, the docks and the circles there, with the blue torch out to look for hidden writing. After a long while the commentary asks for suggestions. A viewer suggests the lighthouse, and another suggests looking up more. From the lighthouse the second diagram shows on a banner hanging on a distant rock face, with a mark in its corner: "that's saying that's move number two, but nothing's actually colored in."
The torches go into a device in the lighthouse that aims at the banner. The blue one changes nothing. With the other torch in, the banner catches fire.
"I'm glad that the game didn't let me do that by accident." Afterward the commentary counts eight marked spots ("they're all there") and draws them.
Getting the order right
Back at the cave wheel, now upside down, the counting starts again. Flipping the numbers alone does not work. Flipping the colored spots as well does not work either. The commentary draws a second grid with the numbers translated so they can be turned on paper: "I'm not good at mirroring." The fourth version keeps the numbers upside down and rotates the little diagram too. This time the wheel takes it: "Yes, okay, epic."
The battery
The gate opens onto the small room. A metal cylinder stands on a square stone pedestal, and lifting it shuts the way out. Setting it back opens the door again. Smaller objects from the inventory go on the pedestal one by one, and none of them keeps the door open: "I need something heavier."
To test whether another battery would do, one gets pulled from a machine elsewhere. "Those lights went out. Did the doors actually close? Okay, the doors actually closed." That idea is dropped.
Where it ends
The bucket goes back to its spot by the round plate, and the commentary's plan is to fill it with "any potion" and use it as the weight. "That's gonna be end of the stream." The video ends in that room, with the battery still on its pedestal in the cave.