Can I use Fiora Legend when it's not my turn?

To determine if you can use Fiora, Grand Duelist (the Legend) when it is not your turn, we must look at how Legend abilities interact with timing rules.

Ruling: Yes, you can use the Fiora, Grand Duelist Legend ability during your opponent's turn.

Reasoning

According to the rules of Riftbound, triggered abilities (which begin with "When..." or "Whenever...") trigger automatically when the specified event occurs.

• Fiora's Trigger: Her ability triggers "When one of your units becomes [Mighty]."
• Timing: Triggered abilities are not restricted by "Action" or "Reaction" speed; they trigger and are placed on the chain whenever the condition is met, regardless of whose turn it is.
• Supporting FAQ: As established in RiftJudge FAQ #942 regarding Sivir's Legend ability (which also uses a "When..." trigger), legend skills that are triggered abilities can be used during the opponent's turn.

How the Interaction Works

If one of your units becomes Mighty on your opponent's turn (for example, if a passive effect or an opponent's card increases your unit's Might to 5+):

1. Trigger: Fiora's ability triggers because a unit became Mighty.
2. Chain: The ability is placed on the chain. You may now choose to exhaust Fiora to "channel 1 rune exhausted."
3. Resolution: Because the ability is now on the chain, it will resolve according to the standard LIFO (Last-In, First-Out) rules, just as it would on your turn.

This is my interpretation based on the mechanics of triggered abilities. While no FAQ explicitly covers Fiora on an opponent's turn, the precedence set by other Legend triggers (like Sivir) confirms that triggered abilities function regardless of whose turn it is.