Raiders' Wake

Oracle Text

Whenever an opponent discards a card, that player loses 2 life.

Raid — At the beginning of your end step, if you attacked with a creature this turn, target opponent discards a card.

Card Rulings

9/29/2017 Raid abilities care only that you attacked with a creature. It doesn’t matter how many creatures you attacked with, or which opponent or planeswalker controlled by an opponent those creatures attacked.
9/29/2017 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 or planeswalker it attacked doesn’t have to still be in the game or on the battlefield, respectively.
9/29/2017 Some raid abilities trigger at the beginning of your end step. These abilities trigger if you attacked with a creature that turn, even if the card with that raid ability wasn’t on the battlefield when you attacked.