When you log into the new Rift Expansion Starfall Prophecy you'll find this waiting on the Store for you to claim.
This seems to be a separate item from the Mystery Tenebrean crate people that pre-ordered were able to get.
Here's what the goodies are:
Void Drake Supply Crate:
Large Artifact Bundle:
Five Individual Rewards Charges:
One Hundred Cosmic Earth Cores:
Wardrobe weapon skin, Scatherran Lily:
All the items are Bound to Account so it doesn't matter which char you claim it on, but of course can only claim the pack once.