Helm of the Fanged Brood

Head equipment — Uncommon

Your Incubation Slaves instead have, "Summon a Spiderspawn for each egg counter removed this way. This deals damage to target troop equal to the number of Spiderspawn created this way."

Changes: Incubation Slave
Slot: Head
Rarity: Uncommon
Set: Shards of Fate
How obtained: Set 1 Chest Loot

What it does is the game's own text; how it was obtained is from the owner's records.