Day 104, 12:00, for 12 hours: 112 zombies at ×22 health and ×25 attack.
Part of Endless tier 21, day 4 of 5.
When it ends: 
All-Purpose Strengthener
Fine Sheet Metal
Scrap Metal
Cold Cuts
Mystery Novel (Endless rewards, tiers 20-29)
Day 104, 12:00, for 12 hours: 112 zombies at ×22 health and ×25 attack.
Part of Endless tier 21, day 4 of 5.
When it ends: All-Purpose StrengthenerFine Sheet MetalScrap MetalCold CutsMystery Novel (Endless rewards, tiers 20-29)