I like this combo. I tried it on jungle Diana and Kayle and it's preety great.
It wasnt used because Warmog for same price allowed you to survive more shots than the active, but since then warmog got nerfed, ohmwrecker buffed and tower damage significantly stronger.
Those items give offense, some defense and good Mregen (same as flat boost from blue: 25 (yes I know it gives 0.5% on top of it)) and allow you to do big plays (Kayle diving under turret for 5 seconds like a boss). Probably not combo to win tournaments with but surprises people on lower elo.