Slitherine

I like the shield wall idea but shield wall is overpowered and makes beating even some human militia slow and tedious. To make it a bit more realistic, and not repeated endlessly, how about making it that if any infantry units in a potential Shield Wall moved more than 2 hexes in a turn the group don't get any shield wall bonus from being adjacent to friendly infantry (this would affect the players' armies just as much as AI controlled armies).

Also it seems bizarre that units that are moving in a random direction due to a bad morale result caused by casualties can accidentally from a Shield Wall with friendly units they accidentally bump into. Would there be any way to change it so that shield wall can only be formed during that side's turn, not due to random movement caused by attacks during the other side's turn

Shield walls should not activate due to a retreat. We'll look into that.

Is there any other effect on Defence that shows the same two iron shields graphic and clanking noise as shield wall? If so could have been that, not sure - looked like it was shield wall activating, but could have been something else with same sound and graphic.

No the graphic and clanking sound is Shield Wall.