I have determined Sentry and Lonely Poro in base. Opponent played Bellows Breath repeated in my base. Do I draw or not? As the Determined Sentry has 1 might and dies first.

To answer your question: No, you will not draw a card from Lonely Poro.

Ruling

When Bellows Breath (with Repeat paid) resolves in your base, it deals 1 damage, then deals 1 damage again as part of the same spell resolution. Because Lonely Poro dies at the same time as Determined Sentry (or while Determined Sentry is still at that location), the "alone" condition for Lonely Poro's Deathknell is not met.

Sequence of Events

1. Spell Resolution: Bellows Breath resolves. It deals 1 damage to your Determined Sentry and 1 damage to your Lonely Poro.
2. Lethal Check: The game checks for lethal damage simultaneously. Determined Sentry (1 Might, 1 damage) and Lonely Poro (2 Might, 1 damage—wait, let's look at the damage).
   • Correction on damage: If Bellows Breath is repeated, it deals two instances of damage.
   • Instance 1: 1 damage to Sentry, 1 damage to Poro.
   • Instance 2: 1 damage to Sentry, 1 damage to Poro.
   • Result: Determined Sentry has 2 damage (lethal). Lonely Poro has 2 damage (lethal).
3. Death Event: Both units are marked for death simultaneously.
4. Deathknell Check: Lonely Poro's Deathknell checks if it was "alone" at the moment of death. Since Determined Sentry was also at the base at the moment of death, Lonely Poro was not alone.
5. Conclusion: The Deathknell trigger does not trigger, and you do not draw a card.

Key Rules

• Rule 741.1: "A unit is alone when there are no other friendly units at the same location."
• Simultaneous Death: As established in RiftJudge FAQ #8617, damage from a single spell (including repeated instances within that spell) is dealt before lethal status is checked. Because both units die at the same time, Lonely Poro is not alone when it dies.