Alice and Nathan are playing a friendly game of magic in a tournament run at Competitive REL. They run into a situation that they don't quite understand, and so they call for a judge. Jason arrives, hears the situation, and now needs to hand down his ruling.
Jason notices that a trigger was missed that would affect his ruling if it were noticed. Should Jason simply assume that the trigger was missed while making his ruling?
Actual Example
Alive controls a Bloodfire Expert. Nathan taps three Mountains and casts Lightning Strike (which only costs {1}{R}). Alice casts Stubborn Denial, thinking that Nathan has no mana to pay. Nathan pays for it, and Alice calls for a judge because Nathan forgot to announce that he had remaining mana in his pool.
Jason arrives, and notices that Alice did not mention the Prowess trigger on Bloodfire Expert. If she had remembered the trigger, Stubborn Denial would simply counter the Lightning Bolt because Alice would meet the conditions for Ferocious. What questions should Jason ask, and how should Jason rule?