BRG is a creature-heavy aggressive midrange deck, so Qarsi Revenant's flying deathtouch lifelink body trades up with almost anything they have, including Smaug the Magnificent and The Sackville-Bagginses. Doomsday Excruciator is a huge flying blocker that stabilizes the board and refills our hand against their grindy sacrifice plan. Duress is less impactful here since much of their deck is creatures rather than key noncreature spells, and Winternight Stories is too slow against their aggression, so both are trimmed for bigger, more resilient bodies.