Day 192, 12:00, for 8 hours: 216 zombies at ×40 health and ×43 attack.
Part of Endless tier 39, day 2 of 5.
When it ends: 
All-Purpose Strengthener
Fine Sheet Metal
Tempered Glass
Scrap Metal
Cold Cuts
Mystery Novel (Endless rewards, tiers 30-40)
Day 192, 12:00, for 8 hours: 216 zombies at ×40 health and ×43 attack.
Part of Endless tier 39, day 2 of 5.
When it ends: All-Purpose StrengthenerFine Sheet MetalTempered GlassScrap MetalCold CutsMystery Novel (Endless rewards, tiers 30-40)