Which attribute? Not curses anyway, though it seems to have the most desired builds for competitive PvP, the important word being competitive. Lingering curses to reduce healing or corrupt enchantments for massive degen. Have tried corrupt enchantments in FA and it is fun enough, could dip into death magic for well of the profane, a single skill well worth the point investment. Having written that last sentence hesitating about crossing curses off the list now, it's a good build to take down Gunther, yeah I'm Luxon. What I settled for is more multi-purpose so I'll keep going for now...
Death magic seems much more fun, but I'm kinda anti-minion, something heroes are good at and I can't be arsed. I know they are not perfect, but they keep enchants on minions better, spirit spamming is the same, good for heroes and tedious for players, suspect both are going to be reconfigured in GW2. That leaves 3 builds: toxic chill, contagion bombers and tainted flesh. Tainted flesh is interesting, but would be a little hard to control in the chaotic CMs, good degen pressure though. Ok so I'm going to discount contagion bombing, even without trying it, but it is limited to JQ.
Played about with toxic chill for a while, a skill bar with an icy-poison theme; there's good synergy between toxic chill and vile miasma, but vile miasma has a long recharge time for only -4 degen. But the notion of skills that interact like that: first a hex (or enchantment) needs to be on the target, then toxic chill poisons the target, and finally vile miasma adding the degen because of the previously applied condition. It's initially engaging, but when you think about it is still 1, 2, 3 in order.
This is likely to make a return in GW2, we've already been told about warrior chains and the levels of adrenaline making additions to skills, but I expect to see the traits adding conditionals to skills as well. I think I prefer this new way, the basic skills need to be interesting and diverse and then conditionals can be added to tweak a build one or another, instead of having to examine, locate and swap skills in and out.
So that leaves blood and soul reaping, which are what I ended up with, but first I need to choose an elite to set the tone of the skill bar.