Okay, lets pretend this map is almost all plane, no big stuff like a hole or something. The bases are north and south. Lets put in a road that goes from S-base base to N-base, + some key-points like shops
( just imagening ) or barracks around the map. Now, lets put this little mountain in the middle of the map where the road goes over, and a mountain in in each side, so there is 2 passages + 1 mountain which you can cross. So the biggest key-point to hold in this map, would be the mountain in the middle.
It would give Defence/Offence to the player holding it.
You could rush over it with some units and kill the enemy forces from behind or above. Or you
could snipe from it with rangers (or catapults, spellcasters - stuff like that) to break the enemys attack though the map. A third strat could be, moving lets say 10 heavy armored untits, and 5 catapults
( if they are gonna be in the game.) up the hill, ( we assume you have control of it), and get in formation.
The armored untits would provide protection to the katapults, and they K's would start attacking their target, f.ks the enemy's portals if they are in range.
A feature i could imagen would be like some towers at certan key-points with random nuetral enemys in it, that you could occupy the tower after killing the enemys in it, with that tower, you would get a bigger line of sight, + ranged defence.
Sorry if my english is bad guys