What I'd like to see down the line, in addition to the parry idea, is the idea of parkour-ish (aka free running) abilities to make vertical movement and environments more dynamic and varied. It may be a bit ambitious for now, but it's something I'd like to see in the future. Each class could accomplish the same effect in different ways; an assassin might scurry up a wall, a necro might turn into a shadow and slide up, and a mage might blink etc. then make it a limited resource, similar to dodge rolling in GW2.
I see this feature being particularly well suited to a post-apocalyptic/near future MMO. A ruined city-scape with a lots of blasted out buildings of various levels could make for some really interesting engagements. I can just see a mage-ish class kiting an assassin-ish class, but instead of simply running away on flat ground he's now often running up or down as well: The mage runs up a stair case, turning to blast the assassin on his heels as he gets to the top. He blinks up to a ledge that constitutes what remains of the ruined 3rd floor of the building. The assassin adeptly runs up the wall, grabs onto the ledge and pulls himself up as the mage continues to flee. The mage blinks across the alleyway separating two nearby buildings, and the assassin makes a flying leap over the dizzying gap in hot pursuit. The mage uses an ability that allows him to safely fall several stories (ex. slow fall) while the assassin jumps and times a roll as he hits the ground to avoid taking damage. etc etc.
