I already wanted the MKII thing to be basically a chest and head "reactor" using magnetic fields to control it's limbs. Let's make it clear that my current idea for magnetism-orientated champion is a melee jungle bruiser.
Plus magnetism opens up so much potential interaction that it can't really live up to it's potential when stuck in adc. ADC spells are usually pretty one-dimensional, with at best one or two interactions between spells, often very loosely. Lucien is probably the most intricate adc to date spell-wise.
I might have a way to incorporate earthy feels for an adc. Meteors is one thing that came to mind, though it might have more potential as a mage, meteors are pretty simple and to the point. Big giant rock falls out of the sky and donks you upside the head. Forces a non-elemental approach though from what I've brainstormed, hard to elemental something of space-origin. Stalact/stalagm-ite usage is another I thought could work. Risks looking too much like Malphite, but I could probably create a skill set using this pretty easily, solely because I can rip some of my ideas from meteors and transplant them over, but being able to make it not a mini-Malphite with a different role is what makes me reluctant to choose it.
A merge of the two seems most plausible, with floaty rocks propelled at high velocity substitute meteors, allowing me to elementalize it, and that's how I can justify sand elemental, by making larger rocks it's form of attack, while the corporeal nature of sand (or just dirt to make it distinctly earthy without being rocks, yet closer than sand to rocks to be more seamless) can be the basis for defensive moves.
Either way, I should first get to typing up the MKII design and getting it on to rito forums. Get my first idea out before I contemplate working on another. Two fully completed ideas are better than 10 half-baked ones.