A really nice sword, crossbow, or sling are good to have around when the zombie apocalypse comes. However, if you've got access to a trebuchet, that's just that much better. But getting and securing one isn't easy, as you'll find out in the Secure the Trebuchet scenario that CMON has released for Green Horde. You can download it for free now.
From the post:
The Orcs are breaching the wall and time is short. We must move the trebuchet to a place where we can eliminate them once and for all! However, we are not strong enough to do so… yet.
This is a scenario for Zombicide: Green Horde, and can prove very difficult. Gather forces around the city to muster the strength to move the trebuchet!