One of the things that virtually every new MMO is trying is some variation on active combat. Effectively, attacks aren’t predestined to hit a target; if you get out of the way, you can avoid the attack.
Now, in a lot of ways, calling this a new development is an exaggeration. MMOs have featured AoEs that you can dodge for years; that’s why “don’t stand in the fire” is a meme, and tanks have long practiced trying to turn the boss away from the group. However, for the vast majority of single target attacks, there was no way to dodge. Due to latency issues, your client and the server might disagree on the precise location of each character in the world, so determining whether someone was in a small area in a brief moment was a much harder calculation than determining whether you were somewhere in a big AoE. So you’d frequently see ranged attacks bending to hit you no matter how you moved: it was predetermined to hit as soon as it was fired, and all you could do was force your client to recalculate the animation.
I’m still not entirely sure how the newer games are getting around this limitation. Likely it involves a lot more processing power and bandwidth spent on minimizing latency issues. In the betas I’ve been playing, the occasional lag spikes do make fights suddenly far more difficult than they would be in an older school game with automatic hits. Regardless, they all seem to be featuring the ability to get out of the way of attacks by moving (and the related effect of making you hit enemies in between you and your actual target).
Another thing all of these active combat systems seems to be featuring is the addition of an active dodge. I personally first saw this in Star Trek Online, basically added as an homage to Captain Kirk, but I think that system was not technically active combat: while you were dodge rolling, the game would just increase your defense stat against attacks. However, in TERA, GW2, and TSW, the dodge roll is a way to move more quickly out of a big attack. All of these games limit pretty heavily how often you can do it, as it can fling you much further away than your normal movement speed would allow. However, I’m not a huge fan of the effect for a crucial reason: most of these games bind the dodge to double-tapping a direction. So I frequently find myself accidentally expending a dodge roll when I start to move in a direction, pause for a moment, and then continue.
And, in general, I don’t wind up using the dodge roll a lot intentionally because simple circle-strafing is often sufficient. My TSW fights with a gun-based character seemed like they should have the Benny Hill theme as combat music: every one of them featured my character running around and around melee targets firing pistols at them point blank. GW2 is a little bit better, simply because more enemies want to stay at range and there are often other players around to body-block melee opponents; you’ll still want to keep moving, but it’s at least in a more believable fashion.
Ultimately, the active combat systems do accomplish a cherished goal of making fights feel more dynamic. Keeping your character moving is almost always a good idea, and you’re trained from very early on to watch out for enemy wind-up attacks and AoE markers so you may not have to wait until your raid leader is is screaming at you to learn to stay out of the fire. And more moving players means more moving monsters, which makes the whole thing feel even more dynamic. However, given that the tradeoff is a complex system to account for latency and that fights can suddenly become impossible with a bad connection, I’m not totally sure this generation of MMOs is going to be able to pull the feature off as well as it would like. It feels more like a gimmick than a really necessary feature, and it remains to be seen whether it will survive to the next generation as a thing that all MMOs must have.