During a showdown at one battlefield, can you play an action card to target units on the other battlefield?

Ruling: Yes, during a showdown you can play action cards and target units on either battlefield. There are no restrictions about where you target during a showdown.

Nuances:

• Hidden cards (cards played from facedown zone that were previously hidden) have additional restrictions that limit targeting to the current battlefield
• Non-hidden cards only have their printed restrictions and can target either battlefield during a showdown