Our intrepid adventurers:
Lylas, drow elf rogue thief, level 4
Third, human fighter sentinel, level 3
Narcisso, half elf life cleric level 4
Dravin, human moon druid level 3
Jackson, human earth wizard, level 4
Kargash, half orc ranger hunter, level 3
Also, 2 NPC's are tagging along
Rurik, mountain dwarf totem barbarian, level 4
Filch, human necromancer, level 3. This is Filge from the observatory in the Whispering Cairn. He surrendered to the party and is tagging along. The kids, being Harry Potter fans, renamed him.
Only two small portions of the grimlocks remain, the chieftan and Grallak Kur. The group chose the passage that lead to Grallak Kur, the grimlock priest of Erythnul. A narrow passage decended in a spiral to a small cavern. A 10' tall cliff rose ahead of them that had the warm glow of a fire above. Lylass climbed up silently and peered over the edge. Seeing over a half dozen grimlocks, as well as one with shocking red hair and either tattoos or body paint with it's back to them.
The plan was for everyone to climb up silently and attack! I had a round of stealth and athletics checks rolled, and everyone rolled well, except for Kargash, with a 1 on his athletics check to climb, he got his hands on the lip and was about to pull himself up when he slipped back down in a cascade of rocks, alerting the distracted foes. Everyone else stood ready and rolled initiative.
Dravin rolled high, and charged Grallak Kur, shoulder first, attempting to shove him into the campfire. I did opposed strength checks, and Grallak Kur stood his ground, and cast spirit guardians upon himself. Narcisso ran up next and took a swing with his sword at the grimlock priest, taking necrotic damage from the dark spirits swirling around his opponent. At this point, the rest of the grimlocks surged forwards to the party, 9 of them in addition to the priest. A few hits where taken by the party, and Rurik went into a rage. A couple of the grimlocks fell, and a couple more were wounded.
In the next round, Dravin and Narcisso turned their attentions to the normal grimlocks attacking them, not wanting to feel the effects of the spirit guardians again. Lylass dropped the grimlock confronting Jackson, freeing him up to fire bolt Grallak Kur. Kargash was able to climb up on his second try and fired an arrow at Grallak as well, getting a critical hit! Grallak Kur cast guiding bolt at Dravin, dropping him to 0 hit points. A grimlock dropped Filch right after. Rurik dropped another grimlock, and moved in on Grallak, and he took a guiding bolt cast at 3rd level right to the chest. He was in bad shape, but still raging.
By the 4th round, the regular grimlocks were wiped out, Rurik got a nice hit in on Grallak, while the spirit guardians took Rurik to single digit hit points. Narcisso got a critical hit with his longsword, dropping Grallak to 1 hp, but I figured close enough and he fell!
At this point, the party stabalized Dravin and Filch (Dravin had been successful on 2 Death Saves at this point, Filch having a success and a failure). Everyone was beat up as well, so after searching for loot they decided on a second short rest. Since coming into the Dourstone Mines posing as miners, they left their armor behind, and the drop in AC is catching up to them. Besides some gold and gems, they found an Hourglass of Respite. It was originally a rope of climbing, but they already have one of those, so I replaced it. They just so happened to turn the hourglass over before taking their rest, so they got the effects of it immediately, gaining the short rest in just 2 minutes! They used up all of their remaining hit dice, and Narcisso and Dravin used up a bunch of their spell slots on healing spells.
With that the group moved on to the final grimlock cave, that of the chieftan. He was all alone sitting on a pile of furs stuffing his face full of halucinogenic mushrooms. They got the drop on him and quickly tied him up and slit his throat, all the while he was laughing maniacally and shouting insults and saying "give my regards to Erythnul!".
No more grimlocks remaining, they worked their way around and entered the Labyrinth of Vecna. The expertly crafted walls and floor were in stark contrast to the twisting caves of the grimlocks. They followed a couple of branching passages and found an empty room. They guessed on the location of a secret door, from where another hall had dead ended. After opening it, they heard a voice from around the bend, so Lylass, Third, Narcisso and Dravin went to investigate, the other four stayed in the room. After going down the hall a short while, they were attacked by four kenku!
They lept to attack, calling out to the other party members that stayed put, but when they went to follow, four more kenku ambushed them from behind, gaining advantage on their attacks.
Overall, this fight finished fairly quickly, and also our session.
As far as my "conversion notes" for this one, I just ran Grallak Kur as a priest from the NPC section of the MM. I'm finding those listings a great resource for statting up leveled monsters. Just take the NPC and add any abilities the creature might have on top. Simple! Otherwise, the other grimlocks and the kenku were straight out of the MM, I just upped their numbers for my party.
The fight with the grimlocks saw some use of my critical hit rules. Though the low HP of the grimlocks saw them falling before they would use their Advantage or Disadvantage from crits or fumbles. As a meta-game point that I noticed, players would target foes that scored a crit on them, hoping to drop them before the opponent could attack again with advantage. I could also argue this as "this guy hits hard, I should finish him off first" as opposed to straight up meta gaming.