For your reference, here is a list of ways you can acquire embers. Please let me know if I'm missing a way:
- Opening Adventurer's Lootboxes. This requires a steel black key, saved from pre-update or purchased from LOTRO store.
- Crafting quest: bestowed by Mozhek in Skarhald; rewards 1,000 embers but requires 7 dwarrowgleam shards
- Quartermaster quest: 25 marks of the Longbeards can be turned in weekly for 500 embers
- Reclaiming the Grey: quest, auto-bestowed; quest has at least 3 tiers which each require completing 20 quests on the solo size of the 3 Grey Mountains instances, or in the 4 resource instances. Each tier bestows 500 embers, and the quest resets to tier 1 weekly.
- Fight for the Grey: quest, auto-bestowed; complete each Grey Mountains instance on size 3 or 6 weekly; rewards 750 embers
- Final boss chests: once daily, the final boss chest in each instance will have embers in it; it is unknown whether running it on different sizes or tiers will have embers again; it is unknown whether having favoured pulls left or not will change the amount of embers, or even whether the amount is variable or set. If you have tested any of these unknowns please let me know!
Hope this helps!