If I cast Bellows Breath with Repeat targeting two units at different battlefields (Kaisa at 1 might and Travelling Merchant at 1 might), and my opponent uses Flash to move both units to their base in response, do the units still take damage and die?

Ruling: Yes, both units will still take damage and die. Bellows Breath targets the units themselves, not the location, and the base is a valid location for the spell to affect units.

Sequence:

• You cast Bellows Breath and pay the Repeat cost
• Instance 1 targets Kaisa at Battlefield A
• Instance 2 targets Travelling Merchant at Battlefield B
• Opponent plays Flash, moving both units to their base
• Flash resolves, both units are now at the base
• Bellows Breath resolves Instance 1: Kaisa is checked at her current location (the base), which is valid, and she is "at the same location" as herself, so she takes 1 damage
• Bellows Breath resolves Instance 2: Travelling Merchant is checked at her current location (the base), which is valid, and she is "at the same location" as herself, so she takes 1 damage
• Both units die from lethal damage

Nuances:

• The "at the same location" restriction is a targeting requirement that must be met when the spell is cast, but the spell tracks units to their new location upon resolution
• When only one unit is targeted by an instance, that unit always satisfies "at the same location" with itself, regardless of where it moves
• The base is a valid location for Bellows Breath to affect units (unlike some spells that specifically require battlefields)
• Each Repeat instance is independent and can target units at different locations