Eternal of Harsh Truths — ruling 1

If a creature is attacking a planeswalker, that planeswalker's controller is the defending player. If a creature is attacking a battle, that battle's protector is the defending player.

Eternal of Harsh Truths — ruling 2

An ability that triggers when something "attacks and isn't blocked" triggers in the declare blockers step after blockers are declared if (1) that creature is attacking and (2) no creatures are declared to block it. It will trigger even if that creature was put onto the battlefield attacking rather than having been declared as an attacker in the declare attackers step.

Eternal of Harsh Truths — ruling 3

If multiple creatures block a creature with afflict, afflict triggers only once.

Eternal of Harsh Truths — ruling 4

Afflict causes the defending player to lose life; it's not damage or combat damage.

Eternal of Harsh Truths — ruling 5

Afflict resolves before combat damage is dealt. If this loss of life brings a player to 0 life or less, that player loses the game immediately. A blocking creature with lifelink won't deal combat damage in time to save that player.

Eternal of Harsh Truths : règles, fonctionnement et interactions (MTG)

Eternal of Harsh Truths 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

Afflict 2 (Whenever this creature becomes blocked, defending player loses 2 life.) Whenever this creature attacks and isn't blocked, draw a card.

How it works : Eternal of Harsh Truths

Original English text — Wizards of the Coast / Scryfall

#1July 28, 2023· Wizards of the Coast
If a creature is attacking a planeswalker, that planeswalker's controller is the defending player. If a creature is attacking a battle, that battle's protector is the defending player.
No other card is named in this ruling.
#2July 14, 2017· Wizards of the Coast
An ability that triggers when something "attacks and isn't blocked" triggers in the declare blockers step after blockers are declared if (1) that creature is attacking and (2) no creatures are declared to block it. It will trigger even if that creature was put onto the battlefield attacking rather than having been declared as an attacker in the declare attackers step.
No other card is named in this ruling.
#3July 14, 2017· Wizards of the Coast
If multiple creatures block a creature with afflict, afflict triggers only once.
No other card is named in this ruling.
#4July 14, 2017· Wizards of the Coast
Afflict causes the defending player to lose life; it's not damage or combat damage.
No other card is named in this ruling.
#5July 14, 2017· Wizards of the Coast
Afflict resolves before combat damage is dealt. If this loss of life brings a player to 0 life or less, that player loses the game immediately. A blocking creature with lifelink won't deal combat damage in time to save that player.
No other card is named in this ruling.