I think you have already answered this but I cannot seem to find it anywhere. How do you build Cassiopeia in 3v3 and who is a good jungle you recommend running with her? Thanks for the help.
Jarvan is also great with Cassiopeia.
I don't know Cassiopeia that well, however I think 3 doran's rings and then Rabadon's Deathcap would be pretty good.
Or you could go the tankier route of RoA - Rylai's.