Given that you can also choose a secondary profession for your character, there are a lot of possibilities for character builds, especially if you have both Nightfall and Factions. It can be a little overwhelming for beginners, so researching a few character builds before selecting a sub-class can be helpful.

More Skills
New classes mean new skills, of which there were already a tremendous variety in Guild Wars Gold. Since you can only take 8 skills at a time into combat, a significant part of the strategy is deciding which skill sets your party should take into a mission. Expect to spend some time twinking these choices, because you have access to your Heroes attributes and skills as well.

The drawback to the growing number of skills in the game is that they are getting increasingly complex. For example, one Dervish skill starts with a blast of AOE holy damage, followed by 30 seconds in which all of your attacks do holy damage, and ends with 3 seconds of AOE fire damage. Using a skill such as this effectively can be pretty tricky compared to straightfoward heals and power attacks. You can’t help wondering if they’re all really useful, but then again, finding a good collection of skills is part of the fun.

Heroes at Your Command
Guild Wars Gold has always had NPC henchmen you could use to fill out your party on missions, but Nightfall takes this concept a step further. It introduces a new kind of henchmen called Heroes, which are unlocked as you progress through the storyline and can then be added to your group in any town. Unlike henchmen, Heroes level alongside your character and you have full access to their skills and equipment. You can outfit them and tweak their builds in much the same way that you can with your own character.

In battle you can bring up an action bar for each Hero that gives you access to their skills and a few other controls. You can move them around either individually or as a group by placing flags on the minimap or the play field. It’s nice to have this added control over NPCs, and it adds an entirely new dimension to the game, even though you have to rely on the AI a lot because it’s very difficult to manage more than your own character and a couple Heroes in real time.

Another nice thing about Heroes is that they are a great way to explore the multitude of skills and builds in Guild Wars Gold without giving up a character slot.

One curious aspect of Heroes is that they do tend to encourage solo play, which is a little odd for a multiplayer game. You can complete the entire Nightfall campaign with only Heroes and henchmen if you so desire. Assuming they are at the keyboard, I think even novice players are better than the AI-controlled Heroes, but Heroes are reliable, and they never complain if you suddenly go AFK for 20 minutes.

Missions
The storyline in Nightfall is a little less linear than those of the earlier releases, and choices you make at certain points will lead you down a different mission path. It’s not as freeform as some games, but they’ve opened up the zones somewhat so it feels less like you’re on rails. There are also unique missions associated with the various new Heroes.