Deepwood Locket

Trinket equipment — Legendary

Your Songstring Wardens have, "When a Beast enters play under your control, gain an additional combat phase, followed by an additional main phase."

Changes: Songstring Warden
Slot: Trinket
Rarity: Legendary
Set: Doombringer
How obtained: Siege Pack

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