Assassin/Ninja Viable Cata Build????

https://wynndata.tk/s/EPHB8Z

It had horrid water def but I just slapped a bunch of t6 waters and its now fine

 

Outside of said horrid water def without t6 waters (which doesn't allow you to utilize killstreak as much) yeah it's fine. If you can, I would swap Shocking to Electric Torc/Charm of the Tempest. Also, you can powder for killstreak on the chestplate (t6-t6-w6) and still have positive water defense if you want. In this build I might honestly go atlas+cata since it'll help with the mana sustain from mana steal (it does decrease your hp by about 1k though so you do become more glassy if you choose that), but the mana sustain should be fine as is.

 

LOL a solid 4k multi
https://wynndata.tk/s/42Pu9t