GW has been sharing a lot as of late from the upcoming Craftworld Codex. Its had a fine time showing us the good things but seems to be skimming the truth about what the future rules might actually look like.
We have come across a leak (there is always leaks) that tells a slightly different story about battle focus. Check out what it states at the bottom of the picture.
As you can see from the bottom line, you have to -3" when shifting through AREA terrain. So dipping in and out of those ruins, you can forget about it.
This feels like a harsh blow to us Eldar Players. Unable to shift through area terrain quickly, well, what's the actual point? I honestly feel like someone has sold me a bill of goods and not told me about those hidden terms and conditions. Serious GW, why not show us all the rules??