Benediction of Moons

You gain 1 life for each player.
Haunt (When this spell card is put into a graveyard after resolving, exile it haunting target creature.)
When the creature this card haunts dies, you gain 1 life for each player.

The List

Guildpact

You gain 1 life for each player.
Haunt (When this spell card is put into a graveyard after resolving, remove it from the game haunting target creature.)
When the creature Benediction of Moons haunts is put into a graveyard, you gain 1 life for each player.

"For each player" means for each player currently in the game, which is normally two. A Two-Headed Giant game has four players. In a Free-for-All multiplayer game, players who have been eliminated or who are outside your range of influence don't count toward the total.