When the team arrives, they will be greeted by a staffer sitting near a field of ropes. The staffer will say something like:
"Hello! I'm glad you're here. I am a Marcana investigator. You can help me finish this incantation. In this field are a number of magic circles surrounding some important objects, which you can see on the colored mats. But I can't figure out what to put on the colored mat in the middle. If you can figure out what should be on the center mat it would help me out a great deal. You can see here I've numbered the ropes for our convenience. But whatever you do, please don't move the ropes, and be careful not to trip on them!"
As the staffer talks they will point out various things. First, there are indeed a bunch of ropes snaking around the field. Among the ropes, on small yellow and blue felt mats, are some small molded objects, and there is indeed an empty mat in the center of the field. Close to where the staffer is standing, at the edge of the ropes, are numbered tags attached to the ropes.
There are seven rope circles (although they take circuitous paths) and eight objects, plus the empty pedestal in the center.
Each object represents a relatively simple word: BAT, BIRD, BRAID (as in, a braid of hair), BUS, BUST (as in, a sculpture of a head), DART (as in a throwing dart you might find in a bar), DIRT (a sculpted bowl actually filled with dirt), and RIB (a ribcage with one rib colored red).
Each rope represents a letter (or in one case two letters: 'US'), and encompasses each object that contains that letter (or 'US'), while excluding every other object. Each rope is also numbered (from 1 - 7) with a tag tied to the rope somewhere.
Five of the ropes also encompass the empty pedestal in the center. Those ropes are A D I R and US. If you read those letters in the order of the rope's tag number, you get R A D I US, or "RADIUS", the answer.
If a team is unsure of what an object is, let them know that they can enter what they think an object is into the answer system and it will tell them if they are correct.
If a team still can't figure out what an object is and they've been there for a little while, you can just tell them what the object is if they describe it to you.
If a team is unsure of what to do after they have identified all of the items, ask them if they remember the staffer's name, and if not to ask for it.
If a team is still unsure of what to do, ask them if they remember what a Venn diagram is.
If a team is still unsure of what to do, tell them that the ropes are the circles in a Venn diagram, and the objects are the items inside of the circles.
If a team is still not getting it, tell them that the letters in the names of the objects are what is important.
Below is the pre-beta version of the puzzle, string glued to cardboard. The exact locations of the ropes will not be the same as in the field, but you can get an idea of how things are arranged. If you look closely you can see the names of objects written on the cardboard.
Rope number -> letters
Each rope has a numbered tag. Teams may use this to confirm their data with you. Bolded lines DO contain the center mat (only 3 and 6 do not).
1 - R
2 - A
3 - T
4 - D
5 - I
6 - B
7 - US