Percy Jackson and the Olympians: Legends

Thalia's Pine Tree is the pine tree on the very tip of the camp. As Thalia Grace laid dying after her wound from her fight to save her friends, her father Zeus, God of the skies, Ruler of the Gods, created Thalia's pine tree to not only save his daughter but to stop that from happening again. He created a barrier to protect lost demigods and to keep Camp Half-Blood a safe place from the monsters trying to kill them. After Thalia's resurrection, it still maintains the barrier, now powered by the Golden Fleece instead of Thalia's life force.