Day 80, 12:00, for 24 hours: 261 zombies at ×17 health and ×16 attack.
Part of Endless tier 16, day 5 of 5.
When it ends:
Scrap Metal×5
Broken Glass×4
All-Purpose Strengthener
Fine Sheet Metal
Tempered Glass
Electronic Components×2
Instant Spicy Hotpot
Inspirational Story (Endless rewards, tiers 15-19)