When read by a player, magical runes trigger a catapulting floorboard that propels any creature within a 15 ft radius through the air. Thrown players are propelled 1d20 ft into the air for 1d6 +5 damage. If they hit the ceiling, then they also take 1d6 bludgeoning damage.
Public domain catapult image from Wikimedia. Modifications by Seth Kenlon. Creative Commons cc0.