After playing Imperial Decree I use Bellows Breath on two units and they react with a hidden card Emperor's Divide. Do I damage the units?

To determine if your units take damage, we must look at the chain and the timing of the effects.

The Chain Sequence

1. You play Bellows Breath: You choose up to three units at a battlefield as targets. This places Bellows Breath on the chain.
2. Opponent reacts with Emperor's Divide: Your opponent flips their hidden Emperor's Divide face-up and plays it. This places Emperor's Divide on top of the chain.
3. Chain Resolution (LIFO - Last In, First Out):
   • Emperor's Divide resolves first. It moves the chosen friendly units from the battlefield to their base.
   • Bellows Breath then attempts to resolve.

Ruling on Damage

According to Rule 359.3.e.9 and the logic provided in RiftJudge FAQ #7422 and #9018, when a spell's targets move to a different location (such as from a battlefield to a base) before the spell resolves, the spell's instructions must be evaluated based on the new state of the targets.

• Targeting Restriction: Bellows Breath requires targets to be "at the same location" when played. This is a targeting restriction for playing the spell.
• Resolution: Because the units have moved to the base, they are no longer at the battlefield where they were targeted. Per FAQ #9018, if the targeted units are no longer at the location where they were targeted, you must choose one location where the targeted units are currently present. Since they are now at the base, you can choose the base as the location to resolve the damage.
• Result: You will deal 1 damage to the targeted units at the base.

Interaction with Imperial Decree

Imperial Decree creates a triggered ability that kills any unit that takes damage this turn.

• Because the units take 1 damage from Bellows Breath at the base, Imperial Decree will trigger.
• Per FAQ #8761, Imperial Decree's kill trigger does not require the unit to be at a specific location; it will find and kill the unit even though it has been moved to the base.

Summary: Yes, you will deal damage to the units at the base, and because Imperial Decree is active, those units will be killed by the resulting triggered ability.

This is my interpretation based on the provided rules and FAQs. No official FAQ exists for this specific interaction between Bellows Breath and Emperor's Divide, but it follows the established mechanics for targeting and resolution when units move zones.