I killed him with 3 others from here earlier today, and they said caustic was wrecking him. --- There is one big difference between Call of Duty and Skyrim. Call of Duty adds content each game while Bethesda takes away. -MC2011
Nope, corrosive is doing the same damage. I have a 4800 corrosive smg on me, with my skill buff i get to more than +100% gun damage and it did only 9000~ I am not sure about the damage from a slag weapon BUT he get slagged from a very long time. Shock destroy his shield but that's it. It does normal damage after that. Explosive seems the same. Yup, nothing really work on him.
And since his DoT get stronger, i get killed in the best cast at half his health solo. He might really be ultra invincible without broken gear (alkaline bee, infinity, turret to agro)
so far, slag and reg damg worked for me, but his health still barley moves... its crazy, i use a shock CC to get his shield down, and then mechros slag skill or slagga, then to a reg CC.... its the best i seen so far and i tried, babymaker reload, plasma caster, reload, maggie, infinity, mongol, nothing really seems to damg him all that much...fire is worthless, and corssive/shock seem to not do much better...