What starts a Showdown?

A showdown begins when the control of a battlefield becomes contested and the turn is in a Neutral Open State (meaning no other showdown or combat is currently ongoing).

According to Rule 344 and the associated RiftJudge FAQs, here is the breakdown of what starts a showdown:

1. The Core Trigger

A showdown is initiated when a player performs an action—most commonly moving a unit—that results in them contesting a battlefield they do not currently control (Rule 445).

2. When does it open?

• Combat Showdown: If the battlefield already contains units controlled by an opponent, a combat is staged and the showdown opens as a Combat Showdown (Rule 344.1).
• Non-Combat Showdown: If there are no units controlled by an opponent at that battlefield, it opens as a Non-Combat Showdown (Rule 344.2).

3. Timing and Nuances

• Staging: When you move a unit into a battlefield you don't control, the battlefield is marked as "Contested" immediately. However, the showdown itself is staged and will not officially begin until the Cleanup phase following that action (Rule 323.8).
• Neutral Open State: If a chain is currently resolving or another showdown is already ongoing, your showdown will remain staged until the game state returns to "Neutral Open" (Rule 323.11).
• Reinforcements: Simply moving a unit to a battlefield you already control does not trigger a showdown, as it is considered a reinforcement (FAQ #8066).
• Re-entry: If you move all your units out of a battlefield (losing control) and then move units back in later that turn, that action will contest the battlefield and start a new non-combat showdown (FAQ #10810).

Important: Only one showdown can exist at a time. If multiple are staged, they must resolve one after another (FAQ #10).