Active Combat, Dodging, and Blocking – When any enemy (AI or player) attacks you, you can actively get away from the attack by double tapping in a direction or using a designated hotkey while moving in a direction, by using a spell that makes your character move like a leap or teleport, or even by simply running away. Dodging drains a "charge" from the dodge bar and currently there's 3 charges in the bar. Once you stop dodging it will then start to recharge. Dodging is something that you’ll have to know when to use and when not to. There are also skills that when "held down" will actively block incoming projectiles from their intended target. So this will allow you to "take a bullet" for other players if the situation arises.
If you are moving in a direction, the dodge will take that into account and dodge in that direction. If you are not moving, you will dodge backward. Dodging now also evades attacks, making it a more effective and understandable way to avoid big creature attacks or to get out of AoE spells.
Every skill in the game has now been added into the animation blending system similar to how the Warrior's Chains work. This makes it so every skill can be chain combo'd like an action game, you don't have to wait for the animation to finish in order to use another skill.
Due to the way targeting enemies works in the game, you don't actually have to target anything to use your skills and also if you use a skill that say has a wide swinging arc, it will hit any target in the trajectory much like an action game, so you're not bound to a single target when using a weapon.
There are a lot of intricate mechanics built into the game where distance plays a large role in combat. Here's some examples:
If a Ranger uses a Longbow, the further away from their target they are the more damage they do, similarly if they use a shortbow the closer they are they'll deal more damage. The Engineer has a skill called Blunderbuss that stacks more bleed effects on an enemy the closer they are to the target and the Flamethrower skill does more damage the closer you are as well.
A Warrior has a Burst skill on each weapon and each one does something different depending on the weapon you're using, but the interesting part is the longer you hold down the button the more damage you do, a stun will last longer, you'll immobilize your target longer, or even do 3 different things entirely per each "level" of adrenaline gained.
There are other combat mechanics to take into consideration as well. The Thief has a skill called Heartseeker that does the following:
Heartseeker seems to have three tiers of damage depending on the targets health. The first tier (paired with lowest damage) when the target is above 66% health, the second when the target is between 66% and 33% (median damage between the two), the third when the target is below 33% (with the highest damage).
The Guardian has a skill called Faithful Strike where you leap at your target and if you hit them, you grant regeneration to your nearby allies.
The Elementalist has a skill called Burning Speed where it allows them to sprint and leave a wall of fire in their wake. When that happens any ally can come up to that wall of fire and use it to inflict extra damage, a Ranger could shoot arrows through it and they would catch on fire, a Warrior could swing their axe and fire would be thrown at your enemies. See the Cross Profession Combos section for more on this.
Many, many skills in the game all have some form of extra condition or effect associated with them, they're not simply skills that just do damage with 1-2 skills that might stun or interrupt like most MMOs.
The Skill Bar & Weapon Swapping - Each class has 10 skills, now you must be thinking “WTF ONLY 10?” Well it’s not as simple as “only 10”. Every class can do real time weapon switching (thanks PS3!) in combat, this switches your skills based on the weapon you have equipped.
All but two classes can swap between 2 weapons at a time (read below for the exceptions).
In combat you’re going to be expected to swap your weapon sets to maximize your effectiveness. A Warrior can swap from a Rifle inflicting conditions on a single target starting out and then into a 2h Hammer for AoE damage when his foes close in. You could use a 1h Axe & Shield for quick adrenalin building and high damage attacks, drop back out of the way and switch to Longbow for massive fire AoE damage.
The weapon type you have equipped defines the skills you have in your first 5 slots. Say you're a Warrior and you're using a 1h sword in your main hand and a shield in your off-hand, your first 3 skills will be sword skills while your last 2 will be shield skills. This is a bit different for the Thief though, say you're using a pistol & dagger, the first two will be pistol skills, the third will be a combination of the two weapons and the final two will be dagger skills. If you're using a 2h weapon all 5 skills will be from that weapon.
The Elementalist can only use one weapon at a time and can't swap due to the attunement mechanic, but they end up having access to more skills to make up for the lack of weapon swapping (20). The Engineer also is unable to weapon swap, but instead they can swap out backpack kits, weapon kits, and turrets.
The other 5 skills on the bar are all changeable to whatever you wish; this isn’t locked down at all.
6 - This is always your heal button, you can change this to whatever heal spell you currently have access to.
7-9 - Are your utility skills you can choose from, for the Elementalist this consists of things like Conjuration, ethereal Forms, Glyphs that modify your abilities, and Signets which gives you a passive and active effect once you use it. Warriors have abilities such at Banners that can be placed to buff you and your allies, while Stances buff the Warrior with boons such as Adrenaline gain. Engineers have Backpack Kits that can serve many purposes such as giving you an entire set of Grenade based skills or Med Kits that allow you to throw down bandages for you and your allies.
0 - On your skill bar is always your Elite skill, for now the only one we’ve seen of the Elementalist is the Form based ability ‘Torando’ which turns you into a tornado that you can move around dealing massive damage and launching enemies into the air. Rangers have Elite skills such as Alpha Strike that summons three animal companions for a limited amount of time. Guardians can use Sanctuary that creates a protective dome around the player and prevents enemies and projectiles from entering, though your allies can enter it for protection.
So for a single weapon build of an Elementalist you’d generally have 44 spells to use. In total with all of the weapons accounted for, you could be managing 139 unique spells based on your second hotbar setup. Ultimately this is something you’ll need to learn because you will be expected to fill any role at any time.
The Downed State & Death – When you run out of health in GW2 you will enter what is called ‘the downed state’. While you are down, you will have 3 skills that are specific to your profession and 1 universal to all professions. If you’re able to kill a mob or help kill a mob while you’re downed you can rally back and get a reprieve so you can keep fighting. If you fail to rally and are overwhelmed you will die, but you can still wait for someone to come resurrect you if you wish, you can also be resurrected while in the downed state. If you do die you can choose to release to whatever nearby waypoint that you have unlocked. While you’re downed nearby allies can come to your rescue and revive you as well. The universal ability is called Bandage, it was put in place in case you go into the downed state and there’s no allies or enemies around for you to rally from.
Underwater Combat – So there’s no more breath bar in GW2, going in the water won’t be an annoying hindrance anymore. You can swim across the surface very quickly, but you’re unable to attack while doing so. If you dive under the surface your entire Skill bar will switch to give you 2 new weapons along with entire new skills for those weapons and even your entire utility bar will change based on what you have slotted for underwater combat. While underwater combat becomes a bit different than while on land, you have access to the entire Z-Axis and you’re able to use spells on the Z-Axis too, not just the X & Y. You might cast a spell that’s a giant beam of light and it will not only damage mobs right where you casted it, but above and below you as well. If you go into the Drowned State while underwater, you’ll get access to a small skill bar that has 4 “Drowning” skills on it. Like the Downed State on the surface, if you manage to kill a mob you will rally back and be able to keep on fighting with all of your skills again. While underwater you can also try to swim to the surface to rally as well, this will give you 25% of your health and you’ll return to your normal state.
You’re also able to pull enemies from the land into the water and this opens up entirely new sets of attacks for them that they otherwise wouldn't have. There’s also tons of content to be found underwater with the Dynamic Event system, not only this but you’ll find entire cities and civilizations as well.
When underwater you’ll be diving into the depths and it might become difficult to tell which way is up or down. As you descend the edges of your screen will become darker and as you ascend that darkness will fade. This makes it quite easy to tell which direction you're headed.