Defense space with three slots?

[Radulf]

The command post has a defense slot, that usually has four slots. However, there is an inlay included, that blocks one slot, allowing only three energy dice for defence. When is that inlay used? So far, I could not see any occasion when it is used.

 

In addition, the VS box includes a two slot defense space for Red Robin to reduce the available slots from three to two, so the three slot space seems to have use in VS mode, but I never found anything.

[Roolz]

IIRC, in the core game, the exertion limits on the villain command board are 3 movement,  4 defense, and 4 reroll (with the adequate cardboard inlays).

For Versus Mode the defense is capped to 3, with a specific inlay. It's most probably the one you're referring to.

 

Regarding the Robin thing, no idea (I don't own the versus mode so I can't check).

[foolio]

I believe that there was one 3slot with the core game, and one with the VS expansion.  The only current use is for VS mode.  You are correct that robin can reduce slots in VS mode.  

[Radulf]

Ah, I kind of suspected the VS mode but never found the corresponding paragraph in the rules. I finally found it at the very beginning. Thank you!