For Manay'a core all party members need Regents items or better (Vision Maker) and a really good Healer that knows what he/she is doing. Even though Regents over Abyss adds like 100 more Defense per item, it is a huge different over Abyss. I am +12 enchantment on all my regents.
I went with a group once, when I was full +12 Abyss, we got rolled cause everyone else was full conjunct +12. Conjunct is PvP gear and has no boss protection or bonuses. At the end, the +12 Abyss got blamed even though I didnt die until the Queen's 2nd form. I stay away from parties that have full conjunct players in instances now.