What have you done?

[Reynhart]

Honestly Dark Art spam for every GCD was zzzzz.

It could have been less boring it it gave you different effect instead of just potency increase. In fact, it never should have given any potency increase because DPS trumps all.
The heal for soul eater, a damage/speed buff from syphon strike, a dot for bloodspiller, an AoE at half the potency/half the blood refill for TBN, etc...This way, you would have spend Dark Arts differently each time.