Day 55, 12:00, for 18 hours: 105 zombies at ×12 health and ×10 attack.
Part of Endless tier 11, day 5 of 5.
When it ends:
Scrap Metal×2
Broken Glass×2
Door Repair Kit
All-Purpose Strengthener
Fine Sheet Metal
Electronic Components
Instant Rice
Entertaining Magazine (Endless rewards, tiers 10-14)