Arena Athlete — ruling 1

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.

Arena Athlete — ruling 2

Heroic abilities will resolve before the spell that caused them to trigger.

Arena Athlete — ruling 3

Heroic abilities will trigger only once per spell, even if that spell targets the creature with the heroic ability multiple times.

Arena Athlete — ruling 4

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.

Arena Athlete : règles, fonctionnement et interactions (MTG)

Arena Athlete is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Heroic — Whenever you cast a spell that targets this creature, target creature an opponent controls can't block this turn.

How it works : Arena Athlete

Original English text — Wizards of the Coast / Scryfall

#1December 7, 2018· Wizards of the Coast
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.
No other card is named in this ruling.
#2September 15, 2013· Wizards of the Coast
Heroic abilities will resolve before the spell that caused them to trigger.
No other card is named in this ruling.
#3September 15, 2013· Wizards of the Coast
Heroic abilities will trigger only once per spell, even if that spell targets the creature with the heroic ability multiple times.
No other card is named in this ruling.
#4September 15, 2013· Wizards of the Coast
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.
No other card is named in this ruling.