Storm Fleet Arsonist
Oracle Text
Raid — When Storm Fleet Arsonist enters the battlefield, if you attacked with a creature this turn, target opponent sacrifices a permanent.
Card Rulings
1/19/2018 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.
1/19/2018 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.
"I'm off to go raiding."
"Oh, where are you going?"
"I don't know. I'll find out after we finish."
"What???"