Oilliphéist

An Oilliphéist is a great Irish serpent or dragon whose passage cuts valleys, churns lakes, and leaves whole landscapes explaining where it went. Some are driven from the land by sacred power; others sleep beneath roads and waters established after their defeat. Waking one converts geography into movement and forces settlements to confront an ancient path beneath their boundaries.

Valley-Cutting Passage: creatures in a 100 ft line make a Quick save. A failure deals 5d10 bludgeoning damage and moves the creature 30 ft to either side.

The Old Route: the Oilliphéist must follow the buried line of its ancient journey. Clearing that route prevents it from entering settlements; blocking the route adds +2 damage to Valley-Cutting Passage.