It does engulf. I need to play a storm sword someday.

Also that guy wasn't talking about a drowning attack type, my bad.

I agree with him, feels like mariners already lose the most out of their terrain (though that net on the log board was looking beastly), it seems reasonable to throw together a water spell on par with drown just for the ranger weapon, and maybe give it to deluge too. Engulf or geyser are probably too much for a ranger staff.