How to break through the Gate of Oblivion on Jebus in week 2?

Hold on! Isn't that how it works? I think that at the start of the game, it decides in which cell of the map a single, upgraded stack will be, and this information is stored in the save files and cannot change on its own. And if this stack disappears, it means that someone attacked this monster stack but didn't defeat it: this is a well-known phenomenon, and, by the way, the rules usually prohibit weakening neutral creatures with this method - that is, if you attack a stack with an upgraded unit, you have to fight to the end!