Shipwreck Looter

Raid — When this creature enters, if you attacked this turn, you may draw a card. If you do, discard a card.

The List

Ixalan

Raid — When Shipwreck Looter enters the battlefield, if you attacked with a creature this turn, you may draw a card. If you do, discard a card.

Raid abilities care only that you attacked with a creature. It doesn't matter how many creatures you attacked with or which player, planeswalker, or battle those creatures attacked.

Raid abilities evaluate the entire turn to see if you attacked with a creature. That creature doesn't have to still be on the battlefield. Similarly, the player, planeswalker, or battle it attacked doesn't have to still be in the game or on the battlefield.