Day 40, 12:00, for 24 hours: 122 zombies at ×9 health and ×7 attack.
Part of Endless tier 8, day 5 of 5.
When it ends: 
Scrap Metal×3
Broken Glass×2
Door Repair Kit
Window Repair Kit
All-Purpose Strengthener
Fine Sheet Metal×2
Electronic Components×2
Instant Rice
Entertaining Magazine (Endless rewards, tiers 8-9)