That was fast.
We have just updated the game with the first Immortal treasure and cursor pack. All Compendium owners should receive them over the next hour or so. Check the level reward schedule to see how to get multiple Treasures.
This treasure includes 7 unique Immortals for Luna, Magnus, Sand King, Spirit Breaker, Pugna, Huskar and a bonus rare Night Stalker item. There is also an extremely rare golden version of the Luna Immortal. Head over to the the Immortal preview page to see short videos of them all.