Possible Suggestions on a Mana Based Juggernaut Concept

So I'm working on a concept of a juggernaut that scales off of mana. I always found Ryze interesting (though personally I find ranged champions boring+he's always been a bit of a balancing nightmare because of his range, low cooldowns and deceptive tankiness. Also that snare.) I was thinking about a spellsword. Not your typical swift moving, mobile spellsword. But more so, a heavily armored, two-handed sword wielding warrior whose blade/himself who is infused with magic.

Now, mana scaling is one part of it, but would I be better off going with AD or AP?