By now, if you've managed to find this blog you know about unit ranges. You've probably internalized how far away you can stand from an archer before you get poked full of holes and ponied. But one lesson I've learnt from chess is, it's not enough to know how your unit moves, you have to know where your unit controls. At first thought, this seems simple enough.
If your opponent steps in the red area, you win, right? Well, yes. But that's not very helpful.
What if your unit only has 1 range, like a wraith? That's the red area there. That's.. not very useful. But the wraith can move! And his range is the blue area. And so extend one more square for the spaces he can reach, and now you know how far the wraith has influence, how far he can killnom in 1 turn.
One more interesting thing to note is that all the squares your wraith can killnom? They're all the LIGHT squares. The board is kinda like chess, whether intentionally or not, I don't know, but it's true of all boards. Once you see this, you immediately are able to decide how much influence a unit has, and exactly what that influence means.
Similarly, for the necro, he has a sword, so he can kill in 3AP. That means that he can spend 1 AP to move within the blue area, and then he will have an effective range of up to the DARK tiles.
Internalizing this means that you can assess board positions quicker, and not have to work each and every move out - start thinking with tiles!
It's hard to overstate my... ... got a bit carried away there didn't we...