The Underdark was mod 8 in Neverwinter, and now that we're moving up next to mod 12 its getting a bit harder to complete easily. Its still got some kick left in it with the rings available still ringing up as some of the best in the game.
Skirmishes are slower to queue. The justifiably criticized key changes known as 'keygate', have made those skirmishes so unrewarding that they are often not worth doing at all. This is considering the cost of keys in the campaign, and that it takes 20 minutes or so to finish one.
What to do? Ill explain my strategy for finishing this in the modern game:
So lets look at Whats available to do.
These are justifiable for 1 reason only, the rings. If you have your happy share of rising/sudden rings. There really isn't much point anymore, when it comes to the campaign, and there isn't much there for entertainment value after you get into the double digits of repetition.
(Tip:Check out the collections to find the source of the ring you want.)
If you ARE doing these, be sure to make lesser keys. They cost 100 less Faerzress to make, and even at that you only come out 50 ahead after opening a chest.
Don't stress on getting a gold finish. I have won more of my +5 rings through non-gold finishes then with them in the skirmishes. It may in theory raise your chances, but getting non-gold certainly doesn't rule out getting a high end ring. Also if you don't have a key, or dont want to spend one, my own experience seems to show about 50/50 shot at a good ring from just the skirmish itself vs opening the chest.
Demonic Heroic Encounters (DHEs) in:
There is the potential for rings from skirmishes as well. ..but its only in the +1, +2 variety so only worthwhile for salvage or sale on the AH. Its a little AD bonus.
At the same time the DHEs (excepting the SH ones) earn you some campaign currency related to the area that you do them in. Its a good way to speed up the Icewind Dale campaign specifically because 3 daily DHEs earns you reputation as well, which is the time limiting bottleneck for that campaign.
Edit for mod 12b+: Dont even bother with the twisted weapon set anymore. They are far outclassed by even the most basic of modern weapons.
For Ndemo you get to use a lesser demonic key, which is good because it saves you faerzress. You want to be using that faerzress to advance the campaign as much as possible until its through. After that you can keep up a steady trickle of DHEs to maintain your key stockpile.
One thing that makes Ndemo decent to do is the time it takes. A group with 4/10 decent DPS players can finish one in 10 minutes. No tank or DC is really required, its nice but not necessary. In relation to the possible rewards it makes demo well worth it still.