My sister and I have been playing SK together for the past few weeks, and today we finally reached the last 5-2 mission, the royal jelly. It was a disaster, we couldn't get past the second floor of the mission. We're working on upgrading our gear for another run later (sis is getting fused demo and 3 star dark matter and poison bombs, I'm think of getting swiftstrike and dusker/gunslinger instead of 3* cobalt). Does anyone have any other advice or suggestions?
Some specific questions:
I recall hearing somewhere that poisoning the RJ will stop it from absorbing it's minions and healing, is that true?
Is bringing a pepperbox along a good idea?
Would a mixed dusker and gunslinger armor set be workable (and if not, would a swiftstrike buckler make it workable?)
Have you read the wiki page "Damage", to learn the damage types that monsters inflict, and the damage types to which monsters are vulnerable? This is one of the key rules of Spiral Knights.
Yes, Dusker is good armor for this situation, because it protects against normal and piercing damage, which is what slimes inflict. So is the shield that you get from the Snarbolax boss.
You seem to be thinking more about armor than weapons. But you should be thinking more about weapons than armor. What weapons have you been using? Pepperbox, poison bomb, and shadow bombs aren't a bad idea. (Yes, I think you're right that poison prevents the Royal Jelly from healing. My information on the particulars of RJ is out of date.) But you should also be able to kill everything in the Royal Jelly Palace by just charging Nightblade or even Tempered Calibur.
My best advice for the boss fight is: Try to make sure that each knight has three pills and nine good offensive vials --- especially curse, poison, shock, and fire. These can really wear down RJ.