okay are you playing LoME rules, if not get some haradrim bowmen in there, you're going to need some fire power out there!
secondly for me you've spent a bit much on heros. for around the 500 point mark i try and take one power hero and one spell caster. if you're getting rid of one use it to get some bowmen, for the 50 points of dropping the shaman (what i recomend) you can get 8 orc bowman, thats enough to make your opponent make a mkove that perhaps he doesn't want to do, even if it is either tieing up his archers in the shoot phase, or taking a longer route using terrain to cover themseves.
if you want to stick with the 3rd hero i'd take a captain. one of the named ones with 3 might would really help your guys.
i'd also consider getting more spearman and less shields
as for dealing with the troll chieftain transfix it with the ringwraith and then get your mahud in there to really mess it up. but make sure you don't become to focused on it and forget the rest of the battle. let me know how it goes!
