Flowsilver Palace is daily instance for ten-player squads of level 100, Sky Level 1 players (reawakened in the Primal World instance).
JFSP or J:FSP = Judgement (Mode): Flow Silver Palace [1]. For at or near RR9
DFSP is what people call the original form of Flowsilver Palace
Mushi is one of the bosses; Mushi means, among other things, "insect" in Japanese