Day 75, 12:00, for 18 hours: 159 zombies at ×16 health and ×14 attack.
Part of Endless tier 15, 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 Spicy Hotpot
Inspirational Story (Endless rewards, tiers 15-19)