If I use Defiant Dance on a recruit to give it 0 might, and my opponent plays Imperial Decree, when we go to damage will the recruit still deal damage and kill my unit?

To answer your question: Yes, your unit will still be killed by Imperial Decree, but the Recruit will not deal any damage.

Here is the breakdown of why this happens based on the game rules:

1. The Recruit's Might and Damage

According to Rule 443.1.b and 443.1.c, combat damage is calculated using the units' current Might. If your Recruit has been reduced to 0 Might by Defiant Dance, it has 0 Might to contribute to the combat.

• Rule 443.1.d: When assigning damage, you assign an amount equal to the unit's Might. If the Recruit's Might is 0, it assigns 0 damage.
• Rule 404.1: Dealing damage requires a value to be marked on the unit. Since the Recruit has 0 Might, it deals 0 damage.

2. Imperial Decree's Interaction

Imperial Decree triggers when a unit takes damage.

• If the Recruit deals 0 damage: It does not "take" or "deal" damage in a way that satisfies the condition for Imperial Decree to trigger.
• If your unit takes damage from the opponent's unit: If your opponent's unit has at least 1 Might and deals damage to your Recruit, your Recruit will take damage. Because Imperial Decree is active, that damage will trigger the effect to kill your Recruit.

Summary

• Will the Recruit deal damage? No. Because its Might is 0, it cannot deal damage during the Combat Damage Step.
• Will your unit be killed? If your unit takes any amount of damage (1 or more) from the opponent's unit during that combat, Imperial Decree will trigger and kill your unit.

Important Note: Reducing a unit's Might to 0 does not kill it (as confirmed by the FAQ regarding Defiant Dance). However, if that unit takes even 1 damage from an opponent while Imperial Decree is active, it will be killed by the Decree's effect.