Another noob question-Blue x's

[ryk421]

I'm stuck on a lot of the custom maps because there is infinity level terrain with blue x's on it, I can't figure out how to destroy them. I've tried darkbeams and loading anti creeper on top of them.  A few seemed to decay on their own, but then i waited for like an hour for the rest to decay, and nothing happened, and i can't access anywhere on the level (Dig Saving, in particular) So, someone please tell me, what is the deal with the terrain with the blue x's? Thank you very much!

[Grauniad]

usually there are one or more gateways that emit "enemy dig packets". these packets will target terrain with blue "x" marks in them, but can only do so if their path is not obstructed by other terrain or anti-creeper.

[ryk421]

tyvm, so i probably have to let some gateways live, until the blue x's are gone. thanks

[Katra]

Figuring out which one(s) you need to let live can be interesting. And if you need to clear AC from a path shields and makers set to vacuum mode are your friend.