For Royal Jelly you need a powerful sword and lots of poison, and for Lord Vanaduke you need lots of fire resist, among other things. I'm thinking of which gear you would need to go through the Ironclaw Munitions Factory and defeat the Roarmulus Twins.
My first guess for 3-star gear, since it's a stratum 4 boss -
Armor: Elemental Cloak or Surge Breaker Armor
Helm: Elemental Hood or Surge Breaker Helm
Shield: Horned Owlite Shield or Surge Breaker Shield
Weapon 1: Cryotech Alchemer MK II
Weapon 2: Nightblade
This guess is based on the fact that constructs and gremlins all do elemental damage, and a lot of the items from the vendor are related to shock damage.
Anyone who has beaten the boss have any thoughts?
I never really experienced the need for shock resist as anything that applied shock is easy enough to block, and the main source of damage in the fight is from the oodles of missiles pouring out of everything. I do agree with stacking on elemental defense and bringing a shadow damage sword. (Shadow mainly to deal with Quicksilvers.) A gun helps, especially one that freezes for taking out puppies, but if you are paying attention to your surroundings it isn't necessarily needed.