Gravesite
1 Cost
Ongoing: At the start of the draw phase, each player draws a card, then discards a card. Each player who discards an Underworld character card this way gains 1 endurance.

So... If I have 2 (or more) Gravesites in play and I discard an Underworld character, do I gain 1 endurance, or 2 (or more)?

The reason I ask is the use of the words "this way". Drawing a card for Gravesite 1's effect, and then discarding an Underworld character could be interpreted as "Discarding an Underworld character because of Gravesite" (not a specific Gravesite) the "way" is the same for all Gravesite effects in play, and thus gain multiple Endurance.