At what speed does Pack of Wonders trigger? Can it be used as a reaction during opponent's turn or only during your own turn?

Ruling: Pack of Wonders triggers at base speed, which means it can only be activated during your turn when the chain is empty and there is no showdown.

Nuances:

• Cannot be used as a reaction to opponent's actions
• Cannot be used during showdown
• Requires completely empty chain (no active effects resolving)