If an opponent lost life and subsequently lost the game, Belbe's triggered ability still counts that player to determine how much mana to add.

If an opponent loses life before their own postcombat main phase, Belbe will reward their suffering with mana.

If an effect creates an additional combat phase in a turn, it may also create an additional main phase after that combat phase. Belbe's ability triggers at the beginning of each of these postcombat main phases.