Posting another clarification ruling from Matt.
Eucatastrophe reads, "Play when you reveal a chaos token that would reduce your skill value to 0 during a skill test (including the [Auto-fail] token)." Some of us on message boards are wondering whether, let's say, if Calvin Wright was at 0 intellect (with no additional boosts via any other assets or card effects), and Calvin initiated an intellect skill test. Calvin draws any zero or negative chaos token. In this situation the chaos token would cause his skill value to stay at 0, since it's already at 0 and cannot be lowered any further. Would Calvin be able to play Eucatastrophe in this situation? Did the chaos token "reduce the skill value to 0" in this case? What about the same question for a "Wendy Adams" with "Haunted" initiating a combat skill test? She would also have a skill value of 0 before drawing the skill token.
A RAW reading of Eucatastrophe leads me to conclude that in order for you to be able to play it, the chaos token revealed must actually have the potential to reduce your skill value to 0—in other words, your modified skill value must be above 0 at the time you reveal the token, and the token must have a value that would reduce your modified skill value to 0 once it is calculated. In other words, if your skill value is already at 0 and you drew a 0 token, that wouldn’t allow you to play Eucatastrophe, because your skill value wasn’t reduced to 0.
Hope that helps!
Senior Card Game Developer
Fantasy Flight Games