Case 2 will be honoured. A class field, property, or method cannot be dereferenced until the type has been initialized, and the type will not be initialized until the static constructor is completed. The static constructor is, to the best of my knowledge, therefore a blocking call.
http://msdn.microsoft.com/en-us/library/aa645612(v=vs.71).aspx
"The static constructor for a class executes at most once in a given application domain."
See this reply from Eric Lippert: https://stackoverflow.com/a/9399027/2420979 and note that "cctor" is IL for static constructor.
No cctors call MyMethod, directly or indirectly! Now is it ever possible for a static method like MyMethod to be called before the cctor of MyClass completes?
No.
Is that still true even if there are multiple threads involved?
Yes. The cctor will finish on one thread before the static method can be called on any thread.
Can the cctor be called more than once? Suppose two threads both cause the cctor to be run.
The cctor is guaranteed to be called at most once, no matter how many threads are involved. If two threads call MyMethod "at the same time" then they race. One of them loses the race and blocks until the MyClass cctor completes on the winning thread.