Sump was with his mother in Detroit, when Jason, Piper, and Leo crashed Festus there, Sump helped catch them. He wears a fiber glass toga. He also fell in love with Piper, thanks to her charmspeak. He also demonstrates the "squeaky war hammer" to Piper. Afterwards he was killed by Leo but reformed almost as fast due to Gaea controlling the Doors of Death.
|Species:||Centaur | Cyclopes | Dragon | Drakon | Eidolons | Empousa | Fire-Breathing Horse | Giants | Gorgon | Harpy | Hyperborean Giant | Ichthyocentaur | Karpoi | Katobleps | Laistrygonian Giant | Lycanthrope | Merpeople | Nikai | Nymphs | Pegasus | Satyr | Skolopendra | Stymphalian Birds | Telekhine | Blemmyae|
|Friendly Monsters:||Argus | Blackjack | Briares | Chiron | Don | Ella | Festus | Gleeson Hedge | Gray |Grover Underwood | Hippocampus | Mellie | Mrs. O'Leary | Ophiotaurus | Peleus | Scipio | Tyson | Tempest|
|Enemy Monsters:||Agrius and Oreius | Arachne | Basilisk | Charybdis and Scylla | Chimera | Chrysaor | Clazmonian Sow | Colchis Bull | Echidna | Euryale | Geryon | Joe Bob | Kampê | | Nanette | Manticore | Medusa | Minotaur | Nemean Lion | Polyphemus | Sphinx | Stheno | Typhon | Scythian Dracanae|
|Neutral Monsters:||Carnivorous Sheep | Cerberus | Erymanthian Boar | Gray Sisters | Gorgons | Furies | Flesh-Eating Horse | Gryphon | Siren|