The Crystal Cave is the dungeon found on one of the frozen northern islands. It's dominated by harmless lasers, magic braziers, chilling ghosts, and frosted doors. To get through, you'll need to use the lasers effectively to break the ice.
Note: There is a big, bad boss at the end of this dungeon. You might want to beef up your arsenal before trying to tackle it. In addition, you'll need to break a good few crystals, which can take an eternity without a decent pickaxe.
Full-Clearing the Crystal Cave
To start off, we have the main mechanic of the dungeon. You have these little glass orbs that you turn to direct the laser being shone into them. By turning the orbs to direct them at a frozen door, you can melt the ice and proceed—super simple stuff.
After the tutorial intro room, you have a couple of spectral spooks to deal with, then another icy door behind some crystals. Break the crystals, turn the orbs, and proceed into the minecart room. Take a quick trip, slay a couple more spooks, and move on.
In the next room with another minecart, you'll notice a boss key frozen in some ice. Remember that for later.
The next room is one I like to call the berry room. Because of the orbs, obviously. There are two frozen doors to thaw in here, as well as the actual way to progress. The first door is obvious, but the second is hidden just off-screen in the lower-right. Walk down there to reveal another orb and the second door. Behind the hidden door is a chest, but we can't do anything with the obvious door yet, so we might as well ignore it.
Shine the laser back through the entrance door in the lower left, then shine it up through the other door. There's a crystal in the way, so get rid of it. Thaw the ice door in there, then take out a ghost and thaw yet another door. Oh, and while we're at it, head to the bottom of this room and sweep the very bottom wall with a laser of your own (assuming you have it) to access a secret room and get two more chests.
From there, we go up into a dead-end and break one particular little crystal. This one, the one shown right below this paragraph:
With that little jerk of a rock gone, we can proceed. Return to the room the boss key is in and take a fun trip on the mine cart. That crystal originally would have bounced us back, so that's why we cut it down first.
There's another baddie waiting for us at the end. Take it out, then sweep the top wall with your laser to snag a second secret room. Ignore the minecart laser in the next room for now and pass through the forest room to find the orb room (because of all the berries we just passed by). Set them up as seen below to melt the door on the right:
Now go back to a couple of rooms and send the minecart laser rumbling along. Toddle after it, orient the two required orbs so that they thaw the last door in the orb room, and you can claim your prize; the Ice Rod! Oh, and a secret room at the bottom of the room.
So what can we do with this ice rod? Well, simply put, we can freeze things. Most notably, we can freeze those pretty braziers we've seen all over the place. And for some magical reason, the ice from the Ice Rod doesn't melt under the laser's heat. Instead, it refracts the laser. Quickly, to the secrets!
Return aaaall the way back to the second room of the dungeon. Freeze the brazier, turn the orb, and thaw the door for two whole chests of loot. Note: you will have to freeze the brazier twice for the door to thaw all the way.
Now back to the berry room! That obvious ice door is useful now! Melt it, head on through, and freeze the two braziers inside to claim three more chests for yourself.
Ok, ok, we'll actually progress now. Make sure the laser is shining into the room with the boss key again, freeze the brazier, and claim the key. With the key in hand, all that's left to do now is ride the minecart. It's in the same room as the boss key. After that, challenge the boss.
The boss is a tall, tanky ice mage who resists the freezing effect of your flashy new Ice Rod (go figure). They attack by spamming out the same freezing projectiles that all the spooky ghosts have used up until now. Getting hit by one of these is nasty since that freeze will eat up all of your invulnerability frames, so you'll be able to be hit again pretty much immediately after unfreezing. But so long as you brought plenty of healing items with you and you dodge well enough, you should be fine. Just whale on the boss until it goes down, then claim your rewards!
For more help with Forager's many puzzles, check out our other Forager guides!