Day 15, 12:00, for 18 hours: 36 zombies at ×3 health and ×3 attack.
Part of Endless tier 3, day 5 of 5.
When it ends: 
Scrap Metal
Broken Glass
Door Repair Kit
Five-Spice Beef Jerky (Endless rewards, tiers 1-4)
Day 15, 12:00, for 18 hours: 36 zombies at ×3 health and ×3 attack.
Part of Endless tier 3, day 5 of 5.
When it ends: Scrap MetalBroken GlassDoor Repair KitFive-Spice Beef Jerky (Endless rewards, tiers 1-4)