How to visualize compass deviation?
I assume your question is about Declination/Variation, not Deviation that is addressed with the compass correction card.  It's confusing because you are reading the compass card from behind so to speak and you are rotating around the magnet, which is always aligned with Magnetic North, when you turn.
So forget about the magnet alignment and just consider the compass card indication that is telling your where the nose of the airplane is pointing, and think it through this way:
If you are flying straight toward the Magnetic Pole on the 10 Deg E Variation line, your compass heading will be 360/0 Magnetic, and your True Heading will be 10 Deg, because the nose is pointed 10 Deg to the right of the True North Pole with your compass showing 360/0 Magnetic.
If you are flying straight toward the True North Pole, your true heading is 360/0 True, and your Magnetic heading will reflect the fact that you are pointing 10 degrees to the left of the Magnetic Pole in order to point straight at the North Pole.  This will show as 350 on your compass.
Hence the &quot;East is Least&quot; rule for Easterly Deviation (West of the Agonic Line). To fly a specific True Heading, point so that the Compass indicates 10 Deg LESS (least=less=subtract from True for a Magnetic heading to fly) than your target True Heading; to fly 360 True, Point at 350 Magnetic.
So, per your question, if you are flying 360/0 True, that is, pointing straight at the North Pole, your compass will show 350 Magnetic if you are on the line of 10 Deg Easterly Declination/Variation.