Does a showdown start if I move a unit to a battlefield I've already scored at?

Ruling: A showdown does not start if you move units to a battlefield you control, even if you've already scored at it. However, if you move all units out and lose control, then move back in later, a showdown will start (though you won't score another point or get conquering procs).

Sequence:

• If you maintain control of a battlefield, moving units in or out does not trigger a showdown
• If you move all units out, you lose control of the battlefield
• When you move units back in after losing control, a showdown begins
• Control is contested and a showdown starts, but you don't score again or trigger conquering effects

Nuances:

• A showdown only begins when control of a battlefield is contested and the turn is in a neutral open state
• Moving back to a previously scored battlefield after losing control gives the enemy a chance to play an action/reaction
• You can regain control of a battlefield you already scored at in the same turn (units are not recalled)