Is there an area here in the forum (I have not found it yet ._.) Where raid groups come together or is there a large Rosso Raid Discord that is active and you often find a raid group with buff characters?
If you know anything, write it in here or add me to discord JuuChan # 0461
I wanted to start farming all the accessories soon 
It's mostly by chance you get into parties in game with buff characters unless you play a buff character yourself (gets you easily in parties). However, there is a raid discord I joined before, but it's private so I'm not sure if the staffs themselves can give you the discord link (my friend gave me the link, but it's not permanent) so that way you can join. It's faster than in-game. I never got any luck getting into raid parties due to my class, but otherwise I wish you luck on finding an active party. Some guilds that I'm aware of do weekly raids after reset so that may help (just an fyi).
Hope this helps
