Arena Athlete

• WWizards of the Coast2013-09-15
  Official Ruling
  Heroic abilities won't trigger when a copy of a spell is created on the stack or when a spell's targets are changed to include a creature with a heroic ability.
• WWizards of the Coast2013-09-15
  Official Ruling
  Heroic abilities will resolve before the spell that caused them to trigger.
• WWizards of the Coast2013-09-15
  Official Ruling
  Heroic abilities will trigger only once per spell, even if that spell targets the creature with the heroic ability multiple times.
• WWizards of the Coast2018-12-07
  Official Ruling
  Resolving Arena Athlete's ability after a creature has blocked won't remove the blocking creature from combat or cause the creature it blocked to become unblocked.

Rulings via Scryfall