Silk Hardened Carapace

Chest equipment — Common

Each of your cards named Zilth have, "When an opposing troop dies, create a Spiderling Egg for each opposing champion and put them into their decks."

Changes: Zilth
Slot: Chest
Rarity: Common
Set: Campaign: Chapter 1
How obtained: Howlings Plains Pack

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