It should be noted that there is a secondary way to get into the area required for this miniquest, although it's incredibly costly. Go to the southwest corner of Lowangen, 3 east, and down to a hidden shop. Buy an apple, it shouldn't matter which. Now, go to the west side of town, and wait and/or move until a worker mentions he's hungry. Give him the apple, and he'll drop his spade. If you wait, this worker will say that he needs a new spade. At last attempt, the only spade which works is the quest spade, which one would almost never want to use. If you give him the spade, he'll dig a way down on the west side of town to the kell area. At this time, we know of no way to get the spade back.
Usual stuff, reagents, mems, having poison gas and diseased cloud handy can be a big help. You will also need a spade and pickaxe for later on. If there are 2 of you, you can rotate damaging and regening, as the Kell Commanders room is a private room.
The Kell Commander encounter
After releasing the kells, go to Lowangen. Go to the hidden shop mentioned above shop and buy the device. Now go outside, drop the device and push it. Each push, it takes 20k gold from your inventory so be prepared for an expensive venture. Keep using the device until you find a tangled tree. Kill the tree to get a tanglevine seed.
Now go to the Palace of Diocletian, give the seed to Admiral Yotln (the retired military man) while being visible. He will give you a medal. You will receive a mail within minutes saying the shop owner wants to obtain the artifact you have just come across. Now head back to Lowangen, go back to the walk-through shop and give him the medal. He will give you a Kell's carapace. Walk outside and remove levitation if you have it on, find the V's (crevasse) and you will fall in. Alternatively, you can just type 'enter chasm', while keeping levitation on. Walk to a room with a vine in it and start digging for a down. Go down and the guard will attack you and remove your carapace from you. Kill him and go down again to the CPK.
The CPK and southwest LPK rooms switch between high regen and no regen. Finally, down from there is non-pk and normal regen, which is where the Kell Commander is. Keep him spelled up, diseased cloud and poison gas the room if you can. And watch out for his high-damage emotes, such as using his scythe to slice you open, hitting extra hard, critically, etc. He will also regenerate chunks of HP if he "regains his strength". Do not wait until you are too low on hp (above 1.5k suggested) or one round from a scythe emote can kill you. It's worth fleeing earlier rather than later, since if you die and the guard has repopped, you can't get back in without another carapace.
The Kell Commander carries: