Can I react to Mushroom Pouch with revealing a Hidden card so it doesn't disappear when Sprite dies?

Ruling: Yes, this works. When Sprite's Temporary trigger and Mushroom Pouch trigger at the start of turn, you can order them so Sprite's Temporary goes on the chain first, then Mushroom Pouch. After Pouch resolves and you draw, you can react with your Hidden card before Sprite dies.

Sequence:

• Put Sprite's Temporary trigger on the chain first
• Put Mushroom Pouch trigger on the chain second
• Resolve Mushroom Pouch (draw a card)
• React with your Hidden card (it turns face-up)
• Resolve Sprite's Temporary trigger (Sprite dies)

Nuances:

• After Mushroom Pouch resolves, you get priority to add reactions because you control the next item on the chain (the Temporary trigger), not because you're the turn player
• The Hidden card must have been placed on a previous turn to have the Reaction tag