If you play Darius and then Challenge an enemy unit with Darius, what is Darius's might during the Challenge - 5 or 7?

Ruling: Darius has 5 might during the Challenge. His "When you play your second card each round" ability is a triggered ability that only resolves after Challenge has finished resolving.

Sequence:

• Darius is played as the first card (5 might)
• Challenge is played targeting Darius
• Challenge resolves with Darius at 5 might
• After Challenge fully resolves, Darius is considered the second card played
• Darius's "When" trigger goes on the chain and resolves, giving him +2 might (now 7 might)

Nuances:

• "When" triggers are triggered abilities that go on the chain, unlike "While" effects which are passive/lingering effects
• A card needs to fully resolve to be considered played for the purposes of counting cards played