Does Minefield count as a discard trigger for Super Mega Death Rocket?

No, Minefield does not count as a discard trigger for Super Mega Death Rocket!.

According to the rules and FAQs for these cards:

1. Definition of Discard: Rule 422.1 defines discarding specifically as moving a card from a player's hand directly into their trash.
2. Minefield's Effect: Minefield's ability instructs you to put the top 2 cards of your Main Deck into your trash. As clarified in RiftJudge FAQ #6746, this is not the "Discard" game action.
3. Super Mega Death Rocket! Requirement: The ability on Super Mega Death Rocket! specifically requires you to "discard 1" (from your hand) to return it from the trash to your hand. Because Minefield moves cards from your deck to the trash, it does not satisfy the requirement for a discard, nor does it trigger any effects that rely on the "Discard" game action.