I had posted some Miasma thoughts earlier and had a few questions asked to me. So I thought ok I will post a walk thru and how I do Miasma.
I use my standard Sampire. Leach life with Vampiric embrace. Mana and stamina through weapon. Miasma has her lowest resist in fire. So first create a weapon with 100% fire damage. I added scorpion slayer to it. Plus SSI, Stamina, and Mana Leech. When you first walk into the Labyrinth be careful not to get too many monitours on you at the same time. I walk in slowly and kill them off as i come to them the spawn slow so no problems. then work my way around the buildings. Miasma is off to the left in a patch of grassy area. Do not make the same mistake I did and accidently lure a reptalon or two onto yourself. The problems with reptalons are they have a nasty firebreath attack and when you are carrying a scorpion slayer which is opposite slayer to reptile slayer you take double damage. OUCH !! OUCH !! Needless to say I was in ghost form alot before I figured out why those damn reptalons where kicking my ass. Now back to Miasma. Once you get in her grassy spawn area. You should only see the occasional Minotour. If you are setup correctly Miasma should drop in 10 or less hits. I use a bladed staff which has the special armour ignore. I spam this on here and leech plenty of mana from her to refill my mana pool. Also Honor is a good thing to do to miasma also want to have 100% damage increase on your suit, ring, bracelet and weapon. Somewhere you want to a complete 100% damage increase total. Miasma drops level 5 t-maps and also treasue chest that have level 6 t-maps to all locations (fel, tram, malas, ilsh, and termur). With the 100% damage incease and scorpion slayer plus honor i can on average take here down about 5 secs and then she has already spawned again. You can not loot her manually fast enough before another has already spawned. she drop on average 2.5k gold so i normally carry a bag of sending with me when i go. in about 15 mins you can have around 15 treasure chests and have already used around 5 uses on a bag sending.
If you have questiones or thoughts post them nd I will add them to theis small write up.