The Clazmonian Sow, which used to be called Phaea, was a savage and formidable wild beast of which by no means should it be an enemy to be laughed at.
The Clazmonian Sow was one of the monsters whose mother was Echidna, who was called mother of monsters. Others relate that Phaea was a woman, a robber full of cruelty and lust, that lived in Crommyon, and had the name of Sow given her from the foulness of her life and manners, and afterwards was killed by Theseus.
Percy Jackson had to face the Sow, right after he defeated the Titan Hyperion , when Kronos and his army sent the sow in to weaken the demigods while his army killed them, and tried to capture Olympus. Percy said that it was like the boar's really angry girlfriend. Percy took a grappling hook and rope from an Athena's cabin camper and swung it around the Sow's wing as it flew away, which left him dangling precariously from the rope as it flew. Blackjack the Pegasus came and let Percy ride on his back so that Percy could pursue the Sow. Percy attached the rope on the Sow's leg to a Hermes statue and then activated Plan Twenty-Three, which made the statue come to life and attack the Sow. Percy then did the same thing with some Lion Statues. Then finally, with the statues' help, Percy defeated the Sow, thus making him the second person to kill the Sow. (The first was Theseus.) Percy said that he hoped it got to meet the "boar of its dreams" down in Tartarus.
The sow is described to be similar to a huge pig with wings, with a cry that was similar to the Erymanthian Boar Percy encountered in The Titan's Curse. Her wings and skin were pink like a flamingo's that destroy all in its path, and she was able to rip up entire forests with her hooves and destroy wildlife with her noxious breath. It belches poisonous gas.
- Annabeth Chase states that no hero has ever been able to defeat the Clazmonian sow, yet Theseus was able to kill the Sow and its owner Phaia, on his way to Athens. However, she said, "As far as I know, no hero has ever beaten it," so it is possible that she didn't hear the legend of Theseus defeating the sow.
- The fact that Percy was able to kill it may have been a reference to the fact that Theseus, who was also a son of Poseidon, was also able to defeat it.