Neheb, the Eternal

• WWizards of the Coast2017-07-14
  Official Ruling
  If an opponent loses life but Neheb leaves the battlefield before your postcombat main phase begins, its last ability doesn't trigger.
• WWizards of the Coast2017-07-14
  Official Ruling
  Neheb's ability checks only how much life opponents lost during the turn, not by how much their life total decreased compared to the start of the turn. For example, if an opponent lost 2 life and then gained 8 life before your postcombat main phase, you'll add .
• WWizards of the Coast2017-07-14
  Official Ruling
  If multiple creatures block a creature with afflict, afflict triggers only once.
• WWizards of the Coast2017-07-14
  Official Ruling
  Afflict causes the defending player to lose life; it's not damage or combat damage.
• WWizards of the Coast2017-07-14
  Official Ruling
  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.
• WWizards of the Coast2017-07-14
  Official Ruling
  You get a postcombat main phase even if no creatures attacked during a turn. Neheb's last ability will trigger.
• WWizards of the Coast2017-07-14
  Official Ruling
  Because it triggers at the beginning of a phase, Neheb's last ability isn't a mana ability. It uses the stack and can be countered by effects that interact with triggered abilities, such as that of Nimble Obstructionist.
• WWizards of the Coast2017-07-14
  Official Ruling
  If you somehow have more than two main phases in a turn, each main phase after your first one is a postcombat main phase, and Neheb's last ability triggers at the beginning of each of them.
• WWizards of the Coast2017-07-14
  Official Ruling
  If an opponent loses life and subsequently loses the game before your postcombat main phase, Neheb's last ability counts that loss of life.
• WWizards of the Coast2017-07-14
  Official Ruling
  Damage dealt to a player causes that player to lose that much life.
• WWizards of the Coast2023-07-28
  Official Ruling
  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.

Rulings via Scryfall