11.9.0
These keys are event rewards or frontier store purchases.
The dungeon opens for one hour and can be farmed.
You can only enter with 3* gunner characters.
Achievements allow to unlock Where Eagles Dare Eddie, but you will need specific characters, including soldier eddie and gunner undead allied soldier and gunner possessed rockets.
Rewards include venom and radiant talismans, and guaranteed evo runes and shards.