2016 Winter Tournament: "Frozen Heart"

I don't know why they're needed – the current walls already prevent jumping. And the hole in the wall is probably a bug in the map generation.

Added 2 minutes later

But where is it actually written in the rules that you can't jump in the game?

I think this point created that impression for me. Apparently, it's incorrect.

10. It is forbidden to use the "Astral Gate" spell to jump from any zone to the opponent's starting zone if the connecting portal/garrison is not breached.