i don't know weather it will be positive suggestion or not but i suggest that there should be separate tactical combat engineers for each of the class...
surroundings effects: hills,rocks it will be nice if they matter in battlefield
there should be defensive engineers OR tactical units which play a role in dense tactics in making location of battlefield more favorable for their forces troops...for example by creating brick walls in several location behind which we can make our tanks to stand and fight and several defensive battle sectors or posts
there should be tactical unit which disinfect the earth with chemicals etc to make a location more favorable for their units
wrath forces:tactical unit which create a electrical shield and generater turret in various location to assist their troops unit during fighting .......
SCOUTS: what about if every heavy unit have his own scouts to spy on his surrounding location