If I use Imperial Decree during my opponent's turn in a showdown where my stunned 5 Might unit takes 4 combat damage from my opponent's 4 Might unit and dies, does my opponent get credit for the kill and trigger their Solari Shrine?

Ruling: No, the opponent does not get credit for the kill. Imperial Decree kills the unit, so the player who cast Imperial Decree (you) gets credit for the kill, not the opponent. Therefore, the opponent's Solari Shrine will not trigger.

Sequence:

• Combat damage is dealt (4 damage to the 5 Might unit)
• Imperial Decree's delayed trigger condition is met
• Imperial Decree's trigger goes on the chain
• The trigger resolves and kills the unit

Nuances:

• The trigger condition (combat damage being dealt) is not the same as the kill action attribution
• The owner of the kill action (Imperial Decree's controller) gets the attribution, not the source that triggered the condition (the opponent's unit dealing damage)
• It doesn't matter who or what triggered the trigger, only who owned the trigger that killed the unit