Raid — War-Name Aspirant enters the battlefield with a +1/+1 counter on it if you attacked with a creature this turn.
War-Name Aspirant can't be blocked by creatures with power 1 or less.
9/20/2014 Once a creature legally blocks War-Name Aspirant, changing that creature’s power to 1 or less won’t change or undo that block.
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.