Why does Red Darius enter untapped when played as the second card?

Ruling: Red Darius enters untapped when played as the second card because triggered abilities (indicated by "when" or "at") trigger after the event they're looking for has fully resolved. When you play Darius as your second card, he fully resolves and enters the board first, then his ability checks if he was the second card played this turn and triggers.

Sequence:

• Play Darius as your second card
• Darius fully resolves and enters the board
• Check for triggered abilities that care about what just happened
• Darius' ability sees that a second card was just played (himself) and triggers
• Darius enters untapped

Nuances:

• All triggered abilities with "when" or "at" timing work this way - they check after the event occurs, not during
• "Play" abilities trigger after a card has been fully resolved and is on the board