If Miss Fortune Captain readies a unit when she moves to attack a battlefield, can that readied unit immediately move into the same showdown?

Ruling: No, the readied unit cannot move into the showdown. The readying trigger goes on the initial chain of the showdown, and by the time it resolves, you are already in the showdown and unable to make standard movements.

Sequence:

• Miss Fortune Captain moves to attack a battlefield
• The readying trigger goes on the initial chain of the showdown
• The showdown begins
• The readying trigger resolves (but it's too late to make standard movements)