Ooooh. Never tried before. Maybe it's with the game engine.
Anyway, I hope there's a save and load system...
You could like, for the quests, add in special conditions. Like in a certain scenario of quests, example, kill the traitor blabla. If you kill him within a certain time limit; or like say...kill him before he kills an irrelevant NPC, you get some additional special reward like gold or extra item, or a ability, or even a level. Failure to achieve quests in special conditions will NOT result in failure of the quests(just missing out some goodies). Ability to complete it with special conditions will result in a message being displayed, and asking the hero to collect his goodie bag from somewhere/or the NPC automatically gives it.
And lets say maybe adapt it from wow where you buy or do quests do get abilities, for better abilities do better quests, or you can even follow what i said in my last post, or have the Imagica RPG style, where you only can have an orb at a time(which the orb provides your abilities).
Maybe you could also add in a Pandarian race. More creativity. Never really seen a Pandarian race in a rpg (Excluding dwarf campaign's panda in the first mission.) Thinking about it, warcraft 3 has quite some preset pandarian models.
And specific items like Horde's Reaver(Example) can only be used by orc brutes/warriors; and Scepter of the Kirin Tor(Example, again) can be used by human mages; and similar race specific items for all the races. Maybe some items could give you akama's/draenais' shadowmeld, which works like permanent invisbility, just that only available at night, which opposite faction's players could use to sneak into your city, and the opposite faction's players would be able to kill side quests NPCs; which in other words would deny you from completing/getting the quest.
Also, maybe like the ability to go inside a factioned tavern/bar/inn/some sort(Each race will have their own style of bar/ furnishing; Orcs will have many spikes and an area where orcs fight to fufill bloodlust, and humans will have more civilised games/sports) where people can heal automatically(as though they were next to a healing ward/fountain) there, but not the opposite factions' heroes.
Just some suggestions...