Zero deaths. Flattened the area beforehand, 2 pieces of iron armor, iron shield, fully upgraded iron mace. Tank and spank, was over in under 4 minutes, 1 health potion used, several Tasty Meads used so I could just keep wacking away without stop.
It's really important to always finish combos with melee weapons as the last hit does double damage.
Upgrading a weapon should always be priority over armor. With a lvl 4 iron mace you would of been doing about 50% more damage per hit. Using a lvl 1 iron mace is what hurt you the most against a regenerating boss.
You walk out of poison clouds.
If his thrown gunk hits altered terrain or trees it doesn't seem to spawn enemies in my experience, as I only had 2 spawns the entire time when it landed in some water just outside my flattened area.