dark arts buff or add new effects to some skills, in resume you use dark arts and you have 10 seconds to use any of the skills that have a dark art effect tie on it to enjoy the bonus effect, when you use a skill with a DA effect the DA effect fades, so is 1 DA=to 1 skill buffed for it.
this is the list:
syphon strike: Dark Arts Combo Potency: 390
power slash: Dark Arts Combo Effect: Increased enmity
souleater: Dark Arts Combo Potency: 440
dark passenger: Dark Arts Potency: 240, Dark Arts Effect: Blind, Duration: 15s
dark mind: Dark Arts Effect: Increases magic vulnerability reduction to 30%
abyssal drain: Dark Arts Effect: Absorbs a portion of damage dealt as HP
carve and spit: Dark Arts Potency: 450
quietus: Dark Arts Potency: 210
bloodspiller : Dark Arts Potency: 540, Dark Arts+Grit Potency: 650
in resume you will use dark arts on power slash at the begining of the combat to gain a significant emity lead, then all you dark arst are for shypon strike, souleater, carve and pit and bloodspiller, you basically get a 140 potency increse on all of then excep for carve and spit how get a 350 potency increse but carve and spit have a recast.
dont let bloodspiller deceive you, the bonus of potency on grit are only to avoid the damage penalty of grit himself, you will not deal more damage on grit for this.
in aoe situations abyssal drain is awesome with dark arts bcs it heal you pretty well, quietus, dark passenger and dark mind are never worthy of waste a DA on it.
the priority is: combat start, DA power slash turn off grit and after that is:
carve and spit > souleater-shypon stryke-bloodspiller >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>dark pasenger,dark mind.
if you tank in grit all the time then same with powerslash and then:
carve and spit > bloodspiller > souleater-shyphon strike >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> dark passenger, dark mind.
on aoes just use unleash to gather all the adds and then spam abyssal drain in the middle of the group, is you need heals or feel you can help you healer more? use abyssal drain with dark arts, remember this combo cost much mana so control that, i hope its helps.