Predecessor Builds > GRIM.exe > Mid Gold Grim

Half caster half ADC, why not? Maybe on high MMR it won't work. But it's good enough to push hard on Gold or even Platinum. Use your blast in assault mode to damage, then recover your mp, when it's low enough with health push, your basic damage is higher than a caster. If he escape GTFO. Use wisely your shield.
You can dominate the mid lane and if you push enough gank on the other lane.
If your ADC it's not good enough, carry the game your own