Step 1 – Challenger’s Proving
At the end of the Challenger Rises quest, collect the new quest from the War Table and listen to Crow and Osiris.
Step 2 – The Umbral Decoder
Visit the Umbral Decoder at the other end of the room and collect Decrypting Darkness quest.
Step 3 – Decrypting the Darkness
Interact with the Umbral Decoder again to collect a message from Tyra Karn, and the Fragile Prismatic Lens.
Step 4 – The Prismatic Recaster
Interact with the Prismatic Recaster, and select Umbral Affinity. Select the Engram under Weapon Focusing, return to the Decoder and decode the Engram you have just focused. Read the new message from Tyra Karn.