How to elongate an area with world edit?

I'm trying to stretch out a hill in world edit and I can't seem to get it to work.

I'm using //deform -o y+=y*2
Which. Unless I'm wrong should deform the vertical axis relative to where I'm standing and stretch it out?

I would really appreciate any help on this matter. I'm a bit lost.
Thanks!

(Also. Unrelated, but does anyone have any idea how to block eating inside a world guard region?)