Crucibles of Malevolence?

[Ouroboros]

What is the point of them? What sort of rewards/benefits does clearing them bring?

[Li Shengshun/Bk-201]

It gives you several items (2-6 from what ive seen) and a good amount of xp.

[Chancho]

you get no xp.

[Steel]

They have a fixed equipment reward for that character (not sure if it's exclusive/unique, probably not considering the fusion system), and a bunch of random drops.

It's a great place to farm equipment (make sure to finish the last mob with a mystic arte if available), but I think items stop dropping after 6-7 attempts, my drops went from 4-6 to 0-1 after I spammed it.

[Riptide [Bastard!]]

mainly the drops and an achievement for doing all of the crucibles

[Kain]

What useful drops this crucibles have? Do i need to complete them several times?

[foolishwtf]

All the mobs in a particular crucible will drop items specific to who runs it. It's not a bad way to quickly farm up specific character items for fusing unnamed items to +99, like sorey earrings or whatever. It's shame the highest level one is for the worst character :(