I would like to note that high ground by himself, without modifiers, pose an inherently advantage against melee fighters, whose turns must be spent not doing what they do best trying to reach elevated enemies, and in a less pronounced way against ranged fighters, whose attacks may be within Long Range (target is hittable but with disadvantage) or be completely out of range, forcing those characters to expose themselves.

As a side note, flanking mechaninc is already present in dos2 engine, albeit in a different manner