Day 39, 12:00, for 12 hours: 30 zombies at ×9 health and ×7 attack.
Part of Endless tier 8, day 4 of 5.
When it ends: 
Scrap Metal
Broken Glass
Door Repair Kit
All-Purpose Strengthener
Fine Sheet Metal
Beef Noodles (Endless rewards, tiers 8-9)
Day 39, 12:00, for 12 hours: 30 zombies at ×9 health and ×7 attack.
Part of Endless tier 8, day 4 of 5.
When it ends: Scrap MetalBroken GlassDoor Repair KitAll-Purpose StrengthenerFine Sheet MetalBeef Noodles (Endless rewards, tiers 8-9)