Can you flip a hidden unit in response to a Sprite with Temporary dying at the beginning of your turn to maintain battlefield presence for scoring?

Ruling: Yes, you can flip a hidden unit in response to the Temporary trigger to maintain a unit on the battlefield for scoring purposes.

Sequence:

• Temporary triggers at the start of the beginning phase
• The trigger goes onto the chain and gives priority
• You can use reactions (like flipping a hidden unit) in response to this trigger
• The Sprite dies when the Temporary trigger resolves
• Your flipped unit remains on the battlefield for scoring

Nuances:

• You are technically reacting to the Temporary effect activating, not to the Sprite dying itself
• Reactions can be used whenever you have priority, regardless of game phase
• The restriction on using cards during ABCD only applies to base speed actions, not reactions
• Opponents can also react to the Temporary trigger