TFG found this weapon at Keep on the Shadowfell.
(I purposefully left out the picture hoping someone will upload that cellphone picture of Finn’s figurine loaded in the trebuchet mini)
Load: (At-Will) Standard action.
Requirement: You must be adjacent to the unloaded trebuchet and have appropriate ammunition, such as a nearby pile of rocks, or a halfling.
Check: Athletics (moderate DC) to load.
Fire: (At-Will) Standard action.
Requirement: You must be adjacent to the loaded trebuchet.
Check: Thievery (easy DC) to fire.
Target: Each creature in an area burst 1 within 40 sq.
Attack: Level +3 vs. Ref
Hit: 2d12 + 1/2 lvl dmg
Effect: Trebuchet becomes unloaded.