The main quest for Season of the Chosen is called Challenger’s Proving. This quest will begin after the A Challenger Rises quest is completed, and players do not need to visit any specific character or vendor to start it.
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.
Step 5 – Return to the War Table
Go back to the War Table for a new message tasking you with finding and killing Basilius the Golem in the Battleground activity.
Step 6 – Battleground: Hailstone
Make your way to Europa and complete the Battlegroud Hailstone event. When you defeat Basilius you will receive the Hammer of Proving.
Step 7 – Return to the H.E.L.M
With the Hammer of Proving in your possession, return to the H.E.L.M via the Director. The Hammer of Proving is a new seasonal item that can be used to get extra rewards during the Battlegound events.
Step 8 – Get Cabal Gold
For the next step, you need to get 14 Cabal Gold. Cabal Gold can be earned by competeing Strikes, Nightfalls, Crucible or Gambit matches, the Blind Well, Nightmare Hunts, Public Events, and Dungeons.
Step 9 – Socket a Medallion
For the next step, you need to socket a Challenger’s Medallion in the Hammer of proving. To do this, right-click on the Hammer of Proving in your quest tab to open it up, then click on the only available Medallion to socket it. This will cost 14 Cabal God.
Step 10 – Pillage Tribute to Caiatl
With the Medallion in place, load into a Battleground event and finish it, then smash the Tribute Chest that spawns at the end of the event with you Hammer.
Step 11 – Focus and Decrypt an Umbral Engram
Hammer Charges that you earn by completing the Battleground and smashing the chest can be used to focus the Umbral Engrams. Make your way to the Prismatic Recaster and focus any Engram you wish, then decode it at the Umbral Decoder.
Step 12 – Return to the War Table
Go back to the War Table to be debriefed by Saladin and the quest is over.