TLDR: Only if you don’t have Atlas. Or if you can do the highest level and really enjoy the flying a lot.
Okay, this is a first attempt at some theorycrafting on dungeon drops.
For this one I’ll be comparing rubies spent on keys for Wraithfire Keep to rubies spent on gold chest in Fortification, since both have pretty similar main drops.
I’ll be using the level 20 dungeon for the math below. It looks like lower level dungeons give worse awards, up to 30% lower. In general, higher level is always better. I have a full sheet of all the drop rates here.
According to that sheet, 400 rubies (20 keys, 2 runs on the max dungeon) will get you:
- 27.19 hours
- 137.5 elemental embers
- 22.5 black pearls
- 1092 of each crafting shard
By comparison, the average gold chests in fort (source) will get you:
- 24.36 hours
- 118.6 elemental embers
- 11.3 black pearls
- 20.5 sigils
- 76.7 egg tokens
- 37.6 fire and ice shards
So at max level dungeons give about 12% more timers, 16% more embers and nearly double the black pearls (still not a lot in total). You also get some crafting shards, not a huge amount, but significantly more than farming beasts will give.
On the other hand you lose out on some sigils, egg tokens, and fire/ice shards.
At this level I think the value per ruby is quite similar. But of course dungeons take time, and gold chests don’t.
At level 14, the rewards have dropped to about equal to chest levels, but of course still missing sigils/tokens. At that point spending rubies is becoming just a waste.
The only exception is if you don’t have Atlas, then the shards are probably worth it even down to the lower levels (still definitely do the max level you can enter and reliably clear).