Beyond Divinity & Divinity II were more like Diablo than Heroes of Might & Magic, but Original Sin went turn-based strategy. Not really grid-based strategy like Heroes. Though they are similar with cooldowns on skills and what not. Although I can't remember specifics of Might & Magic games combat anymore.
I definitely recommend checking it out. The second one at the very least. I haven't played for more than a couple hours because I'm waiting finding a co-op partner. Played through the first Original Sin on PC & PS4 in co-op and while I enjoy the game greatly, the story isn't really particularly good.