In Act 4, the first poison immune monsters showed up: Venom Lords. Guess how I had to kill them ;). Hehe a Megademon boss pack was actually easier to kill than a bunch of Venom Lords.

  Lvl 21 Plains of Despair
I tried to only wake up as few as possible monsters by staying close to the edge of the levels. To my luck Izual was located close to the stairs to the City of Damned. Killing Izual required about 8 minutes, again with the Vengance/Thorns/Poison combo. Smite with a Crushing Blow weapon might have been an option, but at that time I didn't know that this combo works. Thx Ian for the info, I will give it a try :).

The River of Flames had a nasty surprise for UltraLow: Vile Mothers and Childs. These are the hardest to kill monsters so far. It's difficult to make the Mothers turn green because Childs are in the way all the time. Again, I had a hard struggle with myself not to give UltraLow the River of Flames Waypoint, or simply creating new games to get an easier monster mixture. Well it's my own fault ;). Hepasto was as hard as - hmm let's say a pack of 3 Vile Mothers. Got a Shael rune as quest reward; you never can have enough Shaels :).

So let's clear the Chaos Sanctuary. UltraLow triggered the first Exp Shrine in his career - I had avoided all the others before. I wanted to get to lvl 22 before facing Diablo to be able to use the nice fire resist Charm found earlier on. Stupid me - the first Oblivion Knight truncated it ;). The first Boss in the AS was a Venom Lord with Holy Shock/Multishot beside Poison immunity. Hmm does Holy Shock and Multishot stack ? I won't let UltraLow try it out. I lured him out to the RoF, TPed out and came back via the waypoint. The merc killed him over the river while I went to the basement for another bottle of sparkling water.

  Lvl 22 Chaos Sanctuary
The three Seal bosses were a welcomed variation to the normal critters (esp. Venom Lords). The first two had to feel the inevitable poison death, while the Infector was killed with Vengance/Thorns and the help of the merc. So how to beat Diablo ? The merc won't be able to help much even when not directly attacked. With low life and fire resists he won't be able to survive more than two of the fire ring attacks. UltraLow has to do the whole work alone: First try to hit Diablo with a poisoned arrow, then let him feel Vengance and Thorns. Open the inventory screen and keep drinking healing potions. When you start to run out of potions, TP out in a safe area, shop Jamella (super healing potions were available), rinse and repeat. 15 minutes later the job is done. Diablo dropped a Crainte Vomir.