I like the Nautilus changes

But why is his damage being lowered so much?

Nautilus Titan's Wrath (W) damage while shielded decreased to 15/30/45/60/75 from 40/55/70/85/100

That's a pretty unnecessary drop. It was his biggest source of damage contribution and it disappeared the moment his shield popped, which was very easy to do until he gets the gold necessary to stack some health.

I don't think the inclusion of this new jungle tank item is sufficient excuse, with his primary damage source already being on a much higher cooldown than or . While I would certainly think it unfair for these champs to also lose their best method of clearing efficiently(their damage), I do think some consistency should be had and for Riot to explain the context behind his damage being lowered.

At the very least, his scaling damage should be buffed up a bit. Maybe include a percentage of his health similar to the shield itself to allow him to become a more noticeable sustained damage threat.

Riptide (E): cooldown lowered to 6/5.5/5/4.5/4 from 10 at all ranks mana cost lowered to 40/50/60/70/80 from 60/70/80/90/100 AP ratio lowered to .3 from .5 slow duration lowered to 1.25 from 2 seconds

These are good changes. The lowered AP ratio is a little arbitrary, but I'll accept it since I can use my E much more often and hopefully with more efficiency. It's also a pretty strong buff to his ganks if he can get the early CDR to push out multiple E's.

I'm excited to play Nautilus when the PBE comes back up. I'm very hopeful that these will have more positive than negative an impact on his gameplay.