Sources with this icon might be available in the "For You" section of the in-game store. It's random for everyone so we can't know!
Source Name Source Type Rarity Availability
Zombies: Progression Rewards Zombies Epic
Zombies: Richtofen's Rewards Zombies Legendary
Zombies: Undead Siege Drops Zombies Uncommon
Zombies: Undead Siege Hard Only Drops Zombies Epic