oh I see you guys took my idea the wrong way here is an example of what a mountian would do
you have a 3 on a mountain and an enemy has a 4 he attacks you, he rolls 19 while you roll 17 but because of your mountain you actually have 19 so the battles a tie
basically you dont get an extra die just 1 extra point to your roll or whatever
Edit: Either way would work but might make it imposssible to defeat an 8 on a mountian