In order to obtain this key, you’ll have to get Wormsinger Rune first, and defeat hive enemies and a Hive champion. Check out our guide How to use and collect Wormsinger rune. It continues with the Wormfeeder Rune, and your task will be to kill 50 hostile creatures. When you’re done, the game will reward you with a chest key – a random one, sadly. If it’s not the Key of The Spawn, you’ll have to repeat the process. Either that, or roam the Dreadnaught on Patrol and wait for it to drop from an enemy.
Where to find The Spawn Chest
When you’re at the entrance to the Mausoleum, go down the hill on the right and follow the path along the wall to the round balcony. When you get to it, use the Ghost to scan the chasm. You’ll find a path made of invisible floating blocks. Jump on top of them and follow the path. You’ll quickly get to the faraway platform with the chest on it.