The Sky Respawn Anchor lets you set a respawn point in the Aether.
Usage
Charge the anchor by interacting with it while holding Ambrosium Shards. Each shard adds one charge, up to a maximum of 4, and the block glows brighter with every charge.
To bind your spawn point, interact with the anchor with an empty hand (or with an Ambrosium Shard once it is already at full charge). From then on you respawn at the anchor when you die. Each respawn spends one charge — once it runs dry it can no longer respawn you until it is topped up with more shards.