Mystic FAQ: Common Problems and Solutions

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Hello Mystics!

We’re hope you’re enjoying working with MSTY to build our latest dataset. As you may have already realized, MSTY is not perfect, and there are a few special “quirks” that cells in this dataset regularly have. Some of these issues you’ve probably encountered in Eyewire before, and some are brand new!

So without further ado, let’s go through some common problems in MSTY cells and learn how to solve them.

Hitting a Wall

A common problem that is unique to Mystic cells is when traces hit the cube wall, but the branch fails to extend into the next cube.  This is caused by MSTY adding the correct trace to one cube, but failing to add the extension in an adjacent cube.

To fix this problem, you will need to search out the cube that is missing the extension.  We suggest using the “Highlight Children/Parents” function to locate the surrounding cubes, as they can be difficult to identify from the regular overview map.  You will have to click around until you find the cube with the missing extension.  You will know you’ve found the correct cube when the unextended branch is visible inside the bounding box.

Please watch this video for a visual lesson on how to extend these problem cubes.

Slicing and Dicing

Another common problem you will encounter in Mystic cells is the “slicing effect” when you near the edge of the dataset.  Unlike with e2198, each slice near some edges of the zfish dataset has a different end point.  This means that when you scroll through slices in a cube near the edge of the dataset, your branch will be visible in some slices, and off the edge of the slice in others.

With these cubes, try to continue the trace as best you can, skipping over the black 2D slices, and adding the continuation in the visible ones.  Eventually the continuation will become untraceable, at which point it’s time to give up!  Yay!

The Astounding Unclickable Segment

For some reason, some cubes have a section of unclickable 2D slides.  You never know when you’ll come across one of these cubes, or why that 2D is so frustratingly unclickable!  But unclickable it is.  Please make sure to post a note with the cube ID in Mystic Scouts’ Log when you come across one of these cubes.  

There’s nothing you can do to fix this issue, so once you’ve recorded the mischievous cube please continue to grow the other branches as normal.  If you can skip the unclickable portion of the cube and continue to grow the branch out, please do that as well.

The unclickable portion of the 2D usually has a straight boundary that cuts across the slice. See the video below for a visual example of unlickable segments.

All Together Now!

Sometimes, rather than an unclickable section of the 2D you will come across a bug where a bunch of segments have joined together without any rhyme or reason.  Think of it as an AI ubermerger.  If you’re lucky enough to come across this strange circuit-board looking merger mass treat it the same as you would unclickable segments.  Report it in the Scouts’ Log, and try to continue the branch through the cube if possible.

So Close and Yet So Far

This next issue should already be familiar to Scythes.  These are branches that require an extension, but just aren’t quite there.

We’ve all come across “gaps” in branches, where the branch becomes so thin that the AI does not recognize the skinniest part of the branch as a continuation.  When this happens mid-cube, we can just leave a gap and continue to grow the branch using visual cues to find the extension.

Unfortunately, when this happens near the edge of the cube, you have a bit of a Catch-22.  You need to find the extension in the next cube, but the next cube will never grow because no segments are hitting the edge.

In cases like these, you can use a “surrogate” segment to force the spawner to spawn an adjacent cube.  Once the cube has been spawned you will be able to enter the cube, delete the surrogate, and add in the correct continuation.

This is one of the only times when it is acceptable to grow out the branch before MSTY.  This is because when MSTY tries to grow the cube, she will grow the surrogate seed, rather than the real continuation.  Once you have correctly grown out the branch in the “forced” cube, please allow MSTY to continue growing the branch from there.

AI Wonder Twins

Your favorite problem is back and ready for business in Mystic cells!  It’s the return of the AI merger.

That’s right, MSTY still is giving us those good old AI mergers we know and love.  As you know, once the AI has created a merger it is not breakable by players.  Follow the same procedure you would on Eyewire for these types of mergers.  If the merged piece is small and the good piece is large, you can leave it in.  If the merged piece is large or if it hits the edge of the dataset, leave that segment out of the trace.

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That’s all for now, folks!  If you come across any other weird phenomena that you think should be added to this guide, email us at

Thanks to Princeton Tracers @hoodwinked @SeldenK and @sarah.morejohn for the videos and images!

Mystic art by Daniela Gamba