There's a lot of them. Although a bunch of game systems probably have them, especially old and hoary ones.
I'll just pick a couple.
Hyper Rocket Tag. The White Wolf systems tend not to have much of a saving throw/AC mechanic. Or, it's sporadic. So, you'll have situations where with a fairly modest investment on offense, you can be guaranteed to have a potent effect over the target.
I think this is particularly egregious with non-damaging powers, which tend to give you mind control or something like that over the target. And, it's not like these are high level powers. There are a number of rank 1-3 powers (they tend to go from 1-5) that have this effect. Picking one or two of these are a great way to crack out a character with almost no effort.
Action Economy Abuse Abounds: partly related to the above, there are a bunch of important ways to get extra actions or deny targets actions. I think Celerity is actually one of the less powerful ones, mostly b/c people kept on freaking out about it and trying to tweak it (seriously, there are like 5 versions of the damn thing). As a combat tactic, this can be particularly potent b/c unless someone takes an action to dodge or parry, they are basically a sitting duck.
Equipment is Startlingly Potent: another example of the fact that White Wolf authors have some form of brain damage (sorry Justin, but you know it's true ...). In a game filled with hip cool mystic and supernatural entities, there is all sorts of bullshit "mundane" equipment that's really effective. The nWoD is particularly awful in this regard -- like seriously, I want to keep track of my tennis shoes, really ... In short, there's this very effective way of getting stacking or force multiplying firepower by picking the right pieces of equipment, rendering the people who spend character points on things into chumps.
Don't get me wrong. In part due to this thread, and due to Lib himself, I've been thinking about WW a lot. And, there are a lot of WW games I would jump at the chance to play. But, the games don't help you very much. Indeed, they seem to go out of their way to be difficult. Hence the impulse to take what's good and leave the rest behind, Egg Shen style.