From Pathfinder Society Scenario #2-21: In Pursuit of Water, which isn't enabled.

Empowered Blood (3-4)

HAZARD 1

Stealth +2 (untrained)

Description Glowing red Daemonic runes blaze when blood falls on them.

Disable DC 20 Thievery (untrained) to scratch out enough runes to disrupt the magic or Dispel Magic (1st rank; counteract DC 15) to counteract the runes

Siphon Blood

Trigger A creature is reduced to 0 HP in the magic circle

Effect Sezruth (the aghash div in area C) gains 1 Blood Point.

Reset The hazard resets at the beginning of each round until it is disabled.

Pathfinder Society Scenario #2-21: In Pursuit of WaterOGL