Day 57, 12:00, for 8 hours: 68 zombies at ×13 health and ×11 attack.
Part of Endless tier 12, day 2 of 5.
When it ends:
Scrap Metal
Broken Glass
Door Repair Kit
All-Purpose Strengthener
Fine Sheet Metal
Instant Rice
Entertaining Magazine (Endless rewards, tiers 10-14)