Step 4: Prison of Elders or Nightfall
Now, your actions here depend entirely on whether or not you have more than one guardian who is at a high enough level to participate in the new House of Wolves content. If you do, then just repeat the steps above in order to obtain another Armor Core and/or Etheric Light. Once obtained, transfer the items over to the guardian that is being leveled up. It’s as simple as that.
If you don’t have another guardian however, you will have to hope for some serious luck. Completing the weekly Nightfall Strike has a chance to drop an Etheric Light. If the randomness of Destiny shines down upon a player they will have obtained everything they need with just a single guardian (awesome!). If not, then you will need to power level an extra guardian or be patient and wait until next week.
