How does vertical movement work in 40k eighth edition
In 8th you just measure the actual distance you move. It likely will be worth discussing with your opponent before the game how you want to treat different pieces of terrain. Things like if you're going to have to use ladders/stairs or if you both want to just assume any unit can move the 2-4" vertically. Also whether you want to measure diagonal or "L" that is... measure to below where you go up, then directly up. Depending on the terrain you have, it might be easiest to just say going up/down a floor is 3" of movement and not worry about it too much, the main thing is to get on the same page at the start of the game.