first off some classes have loaded movement tables and certain terrain tiles ex: desert have loaded terrain effects.
ex: centaurs treat all 'grassland' type of tiles as zero land effect meaning if your paladin is surrounded by 7 squares of grass in all directions you'll see quite the movement range. dwarves treat hills/desert as 15% and wolfbarons treat forests as centaurs treat grasslands, etc etc.
ugly math version basically reads iirc: take your base move and begin subtracting the % of the adjacent tile follow by the next tile in a outward manner and once the percentages become too great ( over 50%) for your movement (+class considerations & terrain features) you become stopped in that particular direction.
to sum up quickly: what determines a character's movement is: base move score surrounding terrain in a opening circle character's class impassable objects(enemies,mountains,story battle items, etc)
This was all listed over a decade ago in a guide or a thread that had tables showing all classes vs all terrains and the math was presented well. . . doubt i could locate it though it was pre merger lol --- Why in the hell is it so wrong for people to just speak correctly? Don't be so ****ing ignorant. -VeiledGenesis